Full Removable Prosthetics

Making individual spoons for the upper and lower jaw. Fit hard individual spoons. Getting functional impression of the upper and lower jaws.

Individual spoon manufacturing from standard basis plates.

 

Manufactured by the laboratory method the individual spoon.

 

1.	Was take by anatomical cast plaster model	The same as for a spoon from AKR-P	The same as for a spoon from AKR-P
2.	Basis wax, spatula, spirit-lamp.	According with the painted borders from a softened wax to simulate an individual spoon and handle to it on a model.	To check the conformity of borders and accuracy adhering the wax reproduction to a surface of model.
3.	Aditch, bugel, “Izokol”.	To prepare a model for plastering in a ditch by the reverse way and to plaster. To evaporate the wax, to process a ditch by “Izokol”.	To check the durability of model, accuracy of placement a ditch, quality of preparing by “Izokol” after opening a ditch.
4.	The basis plastic.	To prepare the plastic mass, to place on a model, to place under the press, to make a polymerization of plastic.	The correct relation of powder and liquid, to observe the mode of polymerization.
5.	Toolkit and materials for polishing.	To polish the ready individual spoon.	The spoon shouldn’t be the rough and to correspond the borders.

 

One-moment individual spoon by CITO methodic /from wax/.

Forupperjaw.

 

1.

The basis wax, spirit-lamp.

To fold across in three parts the wax plate; to heat and round one extremity and then to bend the tuber of upper jaw in mouth; to push the alveolar process to the palate, to eject, to cool, to cut the surpluses and then again to soften and, controlling a border by cheeks, lips movement, repeat bending, and then to form a back margin after the line “A”.

The wax individual spoon should to solidly adhere to all surfaces of prosthetic field; bypassing cords and bridles of tongue do not come on the movement mucosa.

 

 

Forlowerjaw.

 

2.

The basis wax, spirit-lamp.

Methodic is the same, but the wax plate (2/3 of it) to fold along three times, necessary grasping a retromolar space, and bend it on a model. Along the spoon placing the wire and strengthening it by additional wax roller at the end of forming.

Capturing the retromolar tuber the spoon should to unmovable to be placed on the alveolar process.

                                                              

        

It is having a methodic of individual wax spoon manufacturing by Vasylenko Z.S. It’s differing by shortly margins manufacturing /lower thaeutral zone/, strengthening in the middle by a small portion of plaster.       

               

Nowadays the most widespread is basis individual spoon manufacturing from the self-hardening plastics («Protacryll», «Reodont» etc.).

 

1.

Plaster model, self-hardening plastic, chemical pencil, basis wax, bor-machine, abrasive for plastic.

To paint the borders of spoon on the plaster cast by pencil. To heat the wax plate, densely press out a model and cut out superfluous wax agreeing with borders. A few having blocked its edge to heat again and press a new plate over. Than to put off the wax plates, grease a model by Izokol, mix a plastic, to lay in regular layers on a model and press by the second (upper) wax plate; take off the superfluous of plastic outside of the wax plate margin. After the plastic hardening the margins are processing and manufacturing a handle (on a wax plate can be fixed the bite platens)

Uniform warming of plates, a solid pressing of a model, accuracy margins conformity, elasticity of the plastic dough, full hardening, a good mechanic processing.

 

 

Nature of movements.

Places of corrections.

a/ The tray is pressed against the palate and the patient is asked to move the upper lip and cheek, to make several attempts to remove the tray. b/ The patient is asked to suck a finger and to pull in the cheeks. c/ The patient is asked to open his mouth maximally several times. d/The posterior border on the patient’s palate of determined visually during the utterance of the vowel “A” and then transfer the border on the individual tray

In dropping, shorten the edge in the region of the frenulum of the upper lip and its borders to the premolars. The edge of the tray is shortened in the region of premolars and molars from the vestibular side. The edge above the upper maxillary tuber is shortened.

For the lower jaw.

Nature of movements.

Places of corrections.

a/ The patient is asked to raise the fixed tray by lower lip. b/ The patient is asked to pull in cheeks. c/ The maximum opening of the mouth. g/ Putting out of the tongue in the horizontal direction above the lower lip. e/ Movement of the tongue to the right and to the left. f/ The patient is asked to make several swallowing motions.

The border is corrected in the front part from the vestibular side. Shorten in dropping in the region of premolars from the vestibular side. Shorten in the region of molars and above the retromolar tubercles. Shorten its front edge in the region of the frenulum of the tongue and front teeth. The border is corrected in the region of premolars from the tongue side to the right and to the left. Shorten in the region of molars toward the angle of the lower jaw.

 

 

 

 

 

Having dentures made starts out with impressions of both the upper and lower arches. These preliminary impressions are used to make custom trays that take an even more precise impression of the upper and lower arches. Because dentures are precision fitting prosthetic appliances, only a licensed dental professional should take final impressions with a custom tray. A dental auxiliary can take the preliminary impressions for the custom tray.

Selection of Impression Trays

The patient’s old dentures may be used in selecting impression trays. A slightly oversized tray is needed to cover all of the anatomic landmarks to be registered in the impression. Do not use trays intended for patients with teeth to make edentulous preliminary impressions unless faculty indicate this is appropriate for your patient.

Mandibular tray selection

a. With the patient seated upright, stand to the right and in front of the patient. (Please note this would be reversed for a left-handed student.) Hold the tray in your right hand. Retract the right corner of the mouth with a mouth mirror held in your left hand. Insert the left side of the tray in the mouth rotating the tray to center it over the ridge.

b. When you insert the tray into the mouth, lift the handle superiorly and position the tray so that the posterior portion covers the retromolar pads.

c. Lower the tray anteriorly and observe the adaptation of the tray to the anterior alveolar ridge. 3-5 mm of clearance should exist between the tray and ridge to allow space for the impression material.

Maxillary tray selection

a. With the patient seated upright, stand to the right and slightly in front of the patient. Hold the maxillary tray in your right hand. With a mouth mirror, retract the right corner of the mouth. rotate the impression tray into the mouth. The right side of the tray enters first and as the tray rotates, the outside of the right flange exerts tension against the corner of the mouth allowing gentle tray placement.

b. Move the tray handle inferiorly and place the posterior edge of the tray in the pterygomaxillary notches.

c. move the anterior edge of the tray toward the ridge. you should observe 3-5 mm of clearance between the tray and anterior ridge.

Impression Materials Used for the Preliminary Impression

1. Impression compound (Modeling compound)

2. Irreversible hydrocolloid (Alginate)

Modeling compound: Impression compound is relatively simple to use, has a minimal danger of aspiration, and can be stored for a longer period of time without distortion than alginate. Most importantly, compound impressions can be corrected by additions of small amounts of compound. Alginate cannot be corrected. This allows you to fix small errors in the impression avoiding subjecting your patient to multiple impressions.

The material used for edentulous preliminary impressions in the prescribed procedures is red impression compound supplied in cake form. The softening temperature is 132 degrees F. The water bath is maintained at 140 degrees F. The material should not stay in the water at this temperature any longer than is necessary to make the impression.

Irreversible hydrocolloid. Alginate is used by many dentists for making preliminary impressions. It has greater accuracy of surface detail than impression compound. Edentulous impression trays are available which are designed specifically for use with alginate. The major advantages of alginate are related to its flow properties when easily displaceable tissues are present. It is the material of choice when extreme undercuts exist.

Making the Preliminary Impression

After data collection and treatment plan presentation to your clinical instructor, you will be making preliminary impressions.

This impression will then be used to form a preliminary (diagnostic) cast upon which a final impression tray is made.

Definitions

Anatomic Landmarks Recorded by the Preliminary Impressions

The dentist must be able to identify the anatomic landmarks recorded in the impression. Either the maxillary or mandibular impression may be made first. The mandibular impression is made first if the patient has a tendency to gag.

Steps in Making the Maxillary Preliminary Impression using impression compound

1. Place 1& 1/2 cakes of red impression compound wrapped in a paper towel in the water bath set at 140 degrees F, 5 to 10 minutes prior to impression making.

2. Seat the patient and be sure the patient’s clothing is protected with a napkin.

3. Remove the softened impression compound from the water bath, kneed it, and roll it into a rounded triangular shape. Place it in the previously selected tray and mold the compound with your fingers to the approximate size and shape of the patient’s mouth. Create a grove fro the maxillary residual ridge with your fingers. Be certain to cover the borders of the tray with compound to retain the impression in the tray once the material hardens.

4. Flame the compound surface by passing over it quickly with a torch several times until it is glossy and smooth. this softens the surface layer of the compound and will ensure the accurate reproduction of the tissue surface. Temper the compound in the water bath after flaming to avoid burning the patient. This is accomplished by briefly about 10 seconds) immersing the tray in the 140 degree F water bath.

5. Stand slightly in front of and to the right of the patient. Rotate the tray against the right corner of the mouth. The left corner is reflected with a mouth mirror.

6. Center the tray over the residual ridge so that the tray handle is in alignment with the median line of the face.

7. Apply pressure, using the index finger of one hand, in an upward and backward motion to the middle of the palatal portion of the tray.

8. Discontinue the seating pressure when the impression material has reached the vestibular border.

9. Hold the impression in position with the index finger of one hand in the palate and grasp the cheek with the index finger and base of the thumb of the other hand. Gently pull the cheek outward and downward.

10. Change hands and manipulate the other cheek in a similar manner.

11. Lift the lip outward and downward. Gently massage the outside of the lips with both thumbs to shape the impression in this area. The impression is held until firm (about 30 seconds).

12. raise the cheeks to break the seal and gently push downward on the flange of the impression in the first molar region. It might be necessary to apply a downward and forward pull on the handle of the tray simultaneously. If unsuccessful, ask the patient to close his or her lips and blow air to inflate the cheeks. This will also break the border seal and cause the impression to dislodge.

13. Inspect the impression to determine if it is acceptable. Correct any deficiencies present with the green or brown stick compound.

14. Chill in ice water.

Oral tissue must be in an optimal state of health prior to impression making. To prevent any distortion of the oral tissue by the patient’s dentures, tell the patient to leave the dentures out of the mouth for 24-48 hours prior to the next appointment.

15. Disinfect the impression by placing it into a plastic bag and spraying into the bag with the current surface disinfectant in use in the clinic. Seal the bag for 10 minutes prior to pouring the impression

Checklist for the Maxillary Impression

Landmarks which must be recorded: 1. Residual alveolar ridge 2. Extension into the pterygomaxillary notches 3. Palate covered as far as the vibrating line 4. Extension into the labial and buccal vestibules 5. Extension into the lateral part of maxillary tuberosities 6. Labial and buccal frena Common faults and solutions 1. Incomplete impression of the palate due to insufficient material or failure to seat the impression completely. Correct by adding stick compound or remake the impression. 2. Underextended in tuberosity regions. Correct by adding stick compound. 3. Excess impression material. Remove with sharp knife. Heat and reshape area. 4. Insufficient impression material. Remake impression or correct wtih stidk compound. 5. Deficiency in the labial sulcus because the lip was not lifted forward to allow the compound to flow into the sulcus. Correct with stick compound

Steps in Making the Mandibular Preliminary Impression using Impression Compound

Generally, the mandibular impression procedure is more easily tolerated by the patient. It is often accomplished first to gain the patient’s confidence, especially if the mandibular ridge is parallel to the floor when the mouth is open.

1. Place 1 & 1/2 cakes of red impression compound wrapped in a paper towel in the water bath heated to 140 degrees F, 5 to 10 minutes prior to impression making.

2. Have the patient seated upright.

3. Remove the softened impression compound from the water bath, kneed it, and roll it into a sausage shape. Mold the compound with your fingers to the approximate shape and size of the previously selected tray. make a grove in it with your finger s approximately where the crest of the alveolar ridge will be located. Allow a small amount of compound to cover the tray borders to retain the impression in the tray when the compound hardens.

4. Flame the compound surface by passing over it quickly with a torch several times until it is smooth and glossy. Temper the compound by immersing it in the 140 degree F water bath to avoid burning the patient.

5. Stand in front of the patient and place the tray at the left corner of the mouth. The right corner of the mouth is reflected with a mouth mirror.

6. Rotate the tray into the mouth and carefully center it over the residual ridge.

7. Apply pressure to seat the tray by placing your index fingers over the premolar areas on both sides. Place the thumbs outside the mouth under the mandible for support.

8. As you seat the tray, distend the cheeks in the molar area to make certain they are not trapped beneath the impression material. Use an even downward pressure until the compound has reached the depth of the vestibule.

9. Hold the tray firmly in position and border mold on the right in the area of the buccal frenum by pulling the cheeks upward, inward, anteriorly and posteriorly while the compound is still soft.

10. Change hands and manipulate the left cheek in a similar manner.

11. Now have the patient lick the upper lip from one corner of the mouth to the other corner of the mouth. The impression is held until firm.

12. Loosen the impression after the compound has set by placing the index fingers along the border in the buccal shelf area and gently lift by rotating the fingers along the border.

13. Inspect the impression to determine if it is acceptable. If minor defects or small voids are present, they can be corrected using stick compound.

14. Chill in ice water.

15. Disinfect the impression using current recommended surface disinfectant for 10 minutes in a sealed bag prior to proceeding to the labs.

Oral tissues must be in their optimal state of health prior to impression making. To prevent any distortion of the oral tissues by the patient’s dentures, tell the patient to leave the dentures out of the mouth for 24-48 hours prior to the next appointment.

Checklist for the Mandibular Impression

Landmarks which must be recorded: 1. Retromolar pad 2. External oblique ridges 3. Mylohyoid ridges 4. Extension to the depth of vestibule 5. Extension into the retromylohyoid area 6. Lingual, labial and buccal frena 7. Masseteric notch Common faults and solutions 1. Under-extended tray. Select new tray or modify existing tray. 2. Excess impression material in the floor of the mouth and the labial sulcus. Trim with sharp knife. Reheat compound and replace in mouth. 3. Insufficient impression material in the labial sulcus. Add stick compound. 4. Inadequate extension into the retromylohyoid space. Add stick compound. 5. Wrinkles on impression surface. Remake impression or reflame area and replace in mouth. 6. Tray showing through the impression material. Select new tray or modify existing tray if large.

Steps in Making the Maxillary Preliminary Impression using
Irreversible Hydrocolloid (alginate)

1. Seat the patient and be sure the patient’s clothing is protected with a napkin.

2. Select stock try that will cover all the landmarks indicating the denture bearing area. Also check the impression try and make sure it covers the hamular notches posteriorly.

3. The tray should be lifted in the front. You should observe 3-5 mm of clearance between the tray and anterior ridge.

4. Deficient tray borders should be corrected by adding utility wax.

5. Utility wax can be added to the central portion of the try to act as a guiding stop to seat the tray in place without displacing the mucosa.

6. Mark the hamular notches and the vibrating line (AH line) using the indelible sticks.

7. The alginate is mixed following the manufacturer instructions then loaded into the stock tray. Stand in front of the patient and place the tray at the left corner of the mouth. The right corner of the mouth is reflected with a mouth mirror.

8.The loaded tray should be seated posteriorly first then pushed slowly to the front so that the alginate flows anteriorly. Center the tray over the residual ridge so that the tray handle is in alignment with the median line of the face. At this time the upper lip is elevated so that the alginate flows into the labial sulcus.

9. The seating pressure is stopped and border molding is performed so that the impression is not overextended. The tray is held in place until the alginate has completely set.

10. Remove the impression from the mouth. Inspect the impression to determine if it is acceptable.

11.Disinfect the impression using current recommended surface disinfectant for 10 minutes in a sealed bag prior to proceeding to the labs.

12. Alginate impressions tend to be overextended so the denture outline should be drawn on the impression with an indelible stick. This outline will be transferred onto the cast and will be helpful to fabricate the custom tray.

Checklist for the Maxillary Impression

Steps in Making the Mandibular Preliminary Impression using
Irreversible Hydrocolloid (alginate)

1. Select stock try that will cover all the landmarks indicating the denture bearing area. Also check the impression try and make sure it covers the retromolar pads, external oblique ridge and Mylohyoid ridge.

2. The retromolar pad area should be marked using indelible stick before making the impression.

3. Any deficient area should be corrected by utility wax. The wax should be used on the entire lingual border and retromolar pad to carry the alginate into the lingual sulcus.

4. The alginate is mixed following the manufacturer instructions then loaded into the stock tray. Stand in front of the patient and place the tray at the left corner of the mouth. The right corner of the mouth is reflected with a mouth mirror.

5.Center the tray over the residual ridge so that the tray handle is in alignment with the median line of the face. At this time the upper lip is elevated so that the alginate flows into the labial sulcus.

6.The seating pressure is stopped and border molding is performed so that the impression is not overextended. The tray is held in place until the alginate has completely set.

7. Remove the impression from the mouth. Inspect the impression to determine if it is acceptable.

8. Disinfect the impression using current recommended surface disinfectant for 10 minutes in a sealed bag prior to proceeding to the labs.

9. Alginate impressions tend to be overextended so the denture outline should be drawn on the impression with an indelible stick. This outline will be transferred onto the cast and will be helpful to fabricate the custom tray.

A dimensionally accurate impression is one of the primary determinants for a precise fitting indirect restoration. The clinical success of the indirect restoration requires a precise working model and thus depends upon the accuracy of the final impression.¹ The use of custom fabricated trays with elastomeric impression materials can improve the accuracy of the working model.² There are a myriad of materials and techniques available for custom tray fabrication, including autopolymerizing and heat-activated acrylic resins, thermoplastic resins, and visible light-cured resins. The techniques for custom tray fabrication also vary and range from direct intraoral techniques to indirect laboratory procedures on a primary model.

 

The design and use of the custom tray offers distinct clinical advantages compared to the stock tray. First, dimensional changes that occur during the polymerization of elastomeric impression materials are proportional to the thickness of the material.3 Custom tray design can provide dimensional accuracy and stability by providing a uniform thickness of material throughout the tray.^2,4,5 Utilization of stock trays can result in variations in thickness of the material and the potential for dimensional changes and inaccuracies in the model.^2,4,6 Second, the custom tray rigidity reduces the potential for distortion of the impression in comparison to the flexible stock trays.^7,8 Flexible trays can increase the potential for the impression material to pull away from the adhesive during polymerization of the material and removal from the oral cavity.⁹ Reports also indicate that tray flexure can contribute to impression and cast distortion.^5,10,11 Finally, the custom tray design controls the size and conserves the volume of material required for the impression, reducing the cost of the impression material used for each impression. A streamlined design can reduce discomfort to the patient during the impression procedure because of the smaller design size and reduced volume of material. Furthermore, reducing the volume of elastomeric material utilized can minimize the polymerization-induced shrinkage while offsetting the additional economical costs of the tray fabrication.

CONSIDERATION FACTORS FOR FABRICATION AND UTILIZATION OF THE CUSTOM IMPRESSION TRAY

Visible light-cured resins exhibit dimensional stability immediately after curing, thus allowing immediate clinical use after fabrication.^5,12 Research indicates that autopolymerizing acrylic resins should be fabricated 24 hours before the impression procedure.^5,13 The dimensional stability of elastomeric impression materials is considered to depend on the bulk of material which is the distance from the inner surface of the tray to the surface of the impression.^4,14,15 Elastomeric impression materials are considered most stable when they have a uniform thickness of 2 to 4 mm.¹⁶ Incorporating dental and/or tissue stops can provide a uniform impression material thickness of approximately 2 to 4 mm.

Adapting the visible light-cured resin material directly over the wax spacer may leave a wax residue remaining in the tray. This residue contamination can interfere with adhesion of elastomeric impression materials to the impression tray. Even a small release of the impression material can cause a distortion in the impression, so this is critical. Surface cleaning of the tray using boiling water, pressurized steam and/or a wax remover is suggested. Another recommended method involves burnishing tin foil over the wax spacer.

It is essential that the impression material be securely attached to the tray, especially during removal of the set material from the oral cavity. Surface preparation of the custom tray can significantly affect the retention of the impression material and can improve adhesion between impression material and tray. Methods for improving retention/adhesion include: perforating or roughening of the custom tray surface with tungsten carbide burs and application of adhesive solutions.

         Adhesive drying times of less than 15 minutes reduced the bond strength values of the elastomeric impression materials to the custom tray. To obtain durable and stable adhesion between elastomeric impression material and tray, the drying time after application of adhesive should be at least 15 minutes.^21,22 Also, it is important to remember that each adhesive is specific to the impression material (ie, a polysulfide adhesive caot be used with an addition silicone impression material).

FABRICATION AND UTILIZATION OF THE VISIBLE LIGHT-CURED CUSTOM IMPRESSION TRAY
The main objective in tray construction is to provide a rigid tray for retention of the impression material. The aforementioned consideration factors can provide insight into the optimal fabrication and utilization of the custom tray. A visible light-cured resin material (Palatray XL [Heraeus Kulzer]) was selected for its rigidity, high dimensional stability, ease of manipulation, and unrestricted working time. Also, this material provides the ability to be ideally contoured prior to curing, thus eliminating prolonged finishing times. Other visible light-cured resins include Individo Lux (VOCO), Triad (DENTSPLY International), and Fastray LC (Bosworth Products).

         Fabricating an indirect custom impression tray requires planning, a diagnostic model, and laboratory procedural time. Figures 1 to 10c illustrate the laboratory fabrication and clinical utilization of the visible light-cured custom impression tray that can be used to obtain a precise and predictable final impression.

         Getting functional impression of the upper and lower jaws.

The doctor must  fit an individual spoon, made by a technician,(to adjust, make its surface and edges as much as possible close to the prosthetic bed). Fitting lays in that the orthopedist achieves the maximum stability (a spoon keeps on a jaw) it, “does not fall off” at movements of tongue and cheeks, the spoon edges do not come on a movable mucous membrane. A number of tests of Gerbst (see corresponding methodical recommendations and workbooks) are used for this purpose .

After fitting spoon it is necessary to edge edges with thermoplastic mass (Dentafol) and again to repeat tests of Gerbst. This stage is called registration of borders of an individual spoon.

Further an impression material is selected. The choice of an impression material depends on degree of an atrophy of an alveolar process, its form and the main thing of character of a mucous membrane of an orthopedic field, its degree of a pliability (softness). According to height of edges functional impressions are divided into:

There is not a single method of obtaining an impression, shown in all cases. A technique  of taking compression  functional impression is the most common. Such impressions are necessary to be removed with rigid impression masses – “Dentafol”, plaster, “Ortokor”, “Dentaflex”, “Stomaflex”, etc. The given technique is recommended for a normal or very pliable mucous membrane.

Pressure upon a mucous membrane at removing impression can be carried out either with a hand of the doctor, or chewing muscles of the patient. In the first case an individual spoon is adjusted with the issued borders and filled with impression  mass. Then the doctor enters into an oral cavity and presses a spoon with the mass to an alveolar process, keeping a spoon until the mass hardens. Pressure in each case turns out a miscellaneous and fluctuates even throughout removal impression.

     More uniform load and distinctive for the given patient can be reached as follows. It is necessary to make on a rigid spoon bite platens, fit a spoon, and to define to a toothless patient central occlusion, having lowered bite height a little. To fill a spoon impression with mass and to enter mass with a spoon into an oral cavity. To allow the patient with his own chewing pressure under bite control to keep a spoon in an oral cavity. Pressure will be uniform. It is the best technique.

Under some clinical conditions there is a necessity, on the contrary, to unload a mucous membrane. Such impressions will be decompressive, unloading. They are removed with liquid impression masses – liquid plaster, “Repin”, but an indispensable condition is the punched individual spoon. For this purpose in laboratory to the made spoon the doctor does necessary quantity of apertures by means of a spherical-shaped dental drill.

Decompressive impressions are recommended at very thin atrophied mucous or at the big atrophy of alveolar processes and thickening, easily movable mucous membrane covering an orthopedic field.

The technique of removal differentiated functional impression is known. For this purpose with an individual spoon preliminary impression is removed, then in places, where it is necessary to unload mucous (thickening, a small pliability)  impression mass is removed with a  spatula, or a by-pass channel is made. Liquid impression mass is mixed and again  removal of functional impression is repeated.

Methods of  forming functional impression edges.

 

The most common is the mixed method.

FOR AN UPPER JAW. Individual spoon with impression mass is entered into an oral cavity, grasping maxillary tuberosities (the patient with a half-closed mouth), the spoon is pressed to the palate and an alveolar process with one hand, the second hand the doctor shapes  impression edges from the vestibular side at a half-closed mouth of the patient. Cheeks at lateral teeth are pulled forward and downwards, and at foreteeth the lip is pulled downwards or it is done by the patient. For shaping of edge at the line “A”  the patient is asked to say sounds “A” and “K” at which the soft palate rises upwards. When mass stiffens, the doctor lifts an upper lip, pulling it upwards and simultaneously presses a spoon from top to down at foreteeth then impression is removed from an oral cavity.

FOR A LOWER JAW. A spoon with impression mass is entered and  the patient is suggested to hold covered mouth longer whenever possible . The doctor processes outer side, pulling his cheeks to the field of lateral teeth upwards and forward and a lip in the field of foreteeth – upwards. Processing at tongue side  is made by an active method: the patient is suggested to put out his tongue, with a tongue tip at a half-closed mouth the patient touches cheeks. Impression  is removed this way. The patient is suggested to put out his tongue and simultaneously a lower lip is pulled upwards. Impression is risen and  it is carefully removed.

IMPRESSION QUALITY ASSESSMENT. Impression on the internal surface must not have  sunken places, the edges at vestibular and tongue sides should be of uniform thickness, all places of prosthetic field, which are important for retention (buccal-alveolar space for the upper jaw and the retroalveolar area for the lower jaw), must be accurately taken down, a neutral zone should be precisely outlined. Impression must be clean, free from saliva.

The casts dividing on anatomical and physiological at fully removable prosthetics. The cast, putted off by standard casting spoons without using functional probes for processing margins in calmness, is anatomical. They are dividing on the worker and additional. By the worker manufacturing denture, additional putting off from opposite side for corrects teeth statement. Booth casts will be workers, if prosthetics booth jaws.

Functional cast putting off by individual spoons with functional probes using. They are dividing on functional and functional-suction by the margins height. By mucosa pushing off degree – on compression and uploading.

Can use plaster and alginate materials for anatomical casts. Methodic of pushing off consist in spoon choosing, mix casting mass, putting on the mass on spoon, mixing in enough quality for margins forming. Should to grease selected sites by casting mass by spatula at the expressed upper jaw tubers and high connecting palatum before introduction a spoon in oral cavity. Then by dento-medical mirror delaying a right angle of patient mouth, and casting spoon with mass injecting in right mouth angle pushing backward under sight control against block in front palatum arches and grasping upper jaw tubers. Forcing out remains forward, press down the spoon to palatum by medial and index fingers. Moving its up and backward by left hand forming a vestibular side of cast, soft buccal tissues and upper lip – to forward and down. Asking a patient to repeat this movements. After hardening the casting mass putting off the spoon and estimating a cast from the elastic mass, then should to mould the model. It’s using for individual spoon manufacturing.

Casting methodic from lower jaw differing, because it is injected at first a spoon, down in front part and moving at once in retromolar space; asking a patient to up the end of tongue to palatum, and then put out forward and spend on the border of upper lip by tongue. The margin was process from vestibular side active /by patient/ and passive /by doctor/. Additional cast putted off only if denture manufacturing in one jaw at fully prosthetics.

The individual impression tray, prepared with any method, in the cavity of mouth they compulsorily fit. For this, as a rule, are used the Herbst tests.

                                                                              

FORMING OF THE MARGINS OF THE INDIVIDUAL TRAY IN THE MOUTH OF PATIENTS WHILE USING FUNCTIONAL HERBST TESTS

For the upper jaw:

                                      

Nature of movements.

Places of corrections.

a/ The tray is pressed against the palate and the patient is asked to move the upper lip and cheek, to make several attempts to remove the tray. b/ The patient is asked to suck a finger and to pull in the cheeks.                                                                                      c/ The patient is asked to open his mouth maximally several times.   d/The posterior border on the patient’s palate of determined visually during the utterance of the vowel “A” and then transfer the border on the individual tray

In dropping, shorten the edge in the region of the frenulum of the upper lip and its borders to the premolars.   The edge of the tray is shortened in the region of premolars and molars from the vestibular side.   The edge above the upper maxillary tuber is shortened.

For the lower jaw.

 

Nature of movements.

Places of corrections.

a/ The patient is asked to raise the fixed tray by lower lip.                                                                             b/ The patient is asked to pull in cheeks.     c/ The maximum opening of the mouth.                                 g/ Putting out of the tongue in the horizontal direction above the lower lip.                                                                             e/ Movement of the tongue to the right and to the left.                                                        f/ The patient is asked to make several swallowing motions.

The border is corrected in the front part from the vestibular side.   Shorten in dropping in the region of premolars from the vestibular side.   Shorten in the region of molars and above the retromolar tubercles.   Shorten its front edge in the region of the frenulum of the tongue and front teeth.   The border is corrected in the region of premolars from the tongue side to the right and to the left.   Shorten in the region of molars toward the angle of the lower jaw.

 

Today’s dentists are exposed to a multitude of dental materials, with each manufacturer claiming the benefits and superiorities of its respective products. Sometimes, I feel that the “prehistoric” techniques that we learned in dental school years ago display more benefits than what is in vogue today. This is especially true for crown and bridge impression materials and techniques. One has to only look back and visualize copper band impressions taken with dental compound, and picture the definition, accuracy, margin detail, and meticulous dies that these impressions provided. Eveow, we are still seeing the results of the “copper band masters” decades after the restoratons were placed. I sometimes wonder if the restorations fabricated from today’s materials are as accurate, or will last as long?

     We all know that a meticulous impression is paramount for a precision fit of the permanent indirect restoration. Unfortunately, for many clinicians, taking a crown and bridge impression is one of the most stressful procedures in restorative dentistry. The good news is that taking great impressions can be simple if a dentist chooses the correct impression tray, achieves adequate retraction with controlled bleeding, and uses a rigid impression material with a light body wash to clearly capture every detail of the preparation.

     The purpose of this article is to share material choice rationale and technique protocols that we use in our office for taking consistently accurate impressions.

IMPRESSION MATERIALS

Throughout the last 2 centuries, different types of impression materials have been developed for use in dentistry. The nonelastic materials include: plaster, dental compound, and zinc oxide eugenol pastes. The elastic materials include: alginate (irreversible hydrocolloid), agar (reversible hydrocolloid), polysulfide, condensation silicone, addition silicone (polyvinyl siloxane [PVS]), and polyether.¹

      When evaluating an impression material, dentists tend to focus mainly on 3 factors:hydrophilicity, setting time, and cost. However, there are physical and mechanical characteristics which are far more critical to consider such as: detail reproduction, dimensional stability, ease of removal, gypsum (die and model stone) compatibility, elastic recovery/strain in compression, tear resistance, viscosity, complete conversion to an elastic solid, acceptable odor and taste, shelf life, and having the capability to be poured multiple times while still maintaining accuracy.² Dental marketing seems to be focused on the concepts of hydrophilicity as if it were the only standard on which to judge the product.
     It is also paramount for the dentist to understand that not all impression materials and impression situations are the same. As a result, one should choose an impression material accordingly. The dentist must evaluate what type of impression is being taken (whole arch, sectional, multiple, or single tooth) and chose an appropriate impression tray, method of tissue retraction, and impression material.
     In my opinion, when taking sectional-arch impressions, or when picking up implant impression transfers; a thick consistency putty-like material is preferable, since its rigidity offers greater support. The putty material is a kneadable material that is used as a base material. After a low viscosity material is injected around the tooth, the impression tray filled with putty is then placed over the teeth, displacing the light body (low viscosity), into the crevices surrounding the preparation. After setting, the impression tray is removed, yielding an extremely accurate reproduction.

     The choice of impression materials, coupled with the appropriate impression-taking techniques, is critical to success. In my opinion, it seems that we have traded accuracy for convenience. Most dentists are using disposable plastic trays, as opposed to metal (rigid) ones. Then, the flexible plastic trays are filled with impression materials that flow, rather than with a stiff material that would provide less chance for distortion. This is, in part, due to the manufacturers’ need to have a flowable impression material with a viscosity that works with automix delivery systems (where the base and catalyst are combined and mixed in a small mixing tip). These flowable impression materials lack the rigidity of the previous generation of putty systems that had to be hand mixed.
      Despite the introduction of dynamic mixing devices (cartridges or automated), many dentists still value the consistency of the previous generation of putties and continue to mix their materials manually. Manual mixing putty systems such as Silagum (DMG America), Aquasil Putty (DENTSPLY Caulk), Express Penta Putty (3M ESPE), Flextime and Provil (Heraeus Kulzer), Panasil Putty (Kettenbach LP), and President and Affinis Putty (Coltène/Whaledent) have continued to be manufactured.
      Until recently, I have not experienced an automix impression system displaying the benefits of the copper band technique or the putty systems where the dentist would mix 2 balls of catalyst and base together. (This stiff material, when placed in an impression tray, would displace a light body wash material injected into the sulcus surounding the preparation, resulting in an impression with sharp definable margins.) For clinicians like me, who value a thick consistency, an innovative putty (Honigum-MixStar Putty [DMG America]) has been recently introduced in an automix cartridge that is mixed in an automix machine (MixStar-eMotion [DMG America]) (Figure 1).
     Since I have been using this material in my own practice, I feel that the definition and sharpness of my margins have improved. I do not need to retake impressions as frequently since the stiff putty displaces the light body material easily into the preparation sulcus. As a result, I have now been able to return to my “old school” roots with the benefit of modern convenience. Furthermore, I also find that this putty material, which has neither an unpleasant smell nor taste for the patient, is easier to remove from the mouth than regular heavy body materials. We have found that it maintains excellent dimensional stability and does not distort over time, making it unnecessary for it to be poured immediately. In addition, since dental implants have become a major part of our restorative practice, accurate impressions are vital to the success of these procedures. A firm putty impression system captures the implant transfer postion very accurately. In the dental laboratory, the rigidity provided by the putty allows the transfers to be precisely poured into an analog model (Figure 2).

IMPRESSION TRAYS

Determination of the central correlation of the jaws in the 4th group of dentition defects.  Biomechanics of the mandibular movements. Occlusion causes

The methodology of determining central ratio of jaws at the complete absence of teeth on both jaws:

1. To check up conformity of wax templates with bite rollers  to requirements.

a. Borders of wax templates should correspond to borders of dental prostheses.

b. Templates should adjoin to models densely.

c. The wax roller should settle down strictly on the middle of an alveolar process, width in a frontal area 0.8 – 10.0 mm, in lateral 1 – 1.5 cm, on 2 – 3 mm above the remained teeth.

2. To define interalveolar height an anatomic-physiological method:

a. Paper or a ruler is used. A point is put on a chin of the patient .

b. Then in a condition of physiological rest  this point is transferred on a sheet of paper or a ruler.

c. From 1 to 4 mm is taken away on a ruler or  paper  , depending on age of the patient (a tone of chewing muscles), for reception of height of a bite.

3. With dental spatula   frontal site of upper bite roller  is cut in parallel pupillary line, achieving, that it is on 0,5 – 1 mm below upper lip edge.

1. Lateral sites of a bite roller are cut in parallel each other and tragonasal line.

2. Locks on a roller surface are done.

3. Lower bite roller is cut, achieving, its contact on all plane with upper roller, the height rollers should correspond to height of physiological rest (i.e. on 2 – 3 mm above height biteа) – it is supervised with a ruler.

4. With the help of dental spatula and spirit  warm up bite rollers are warmed up by 2 – 3mm.

5. Warmed up bite rollers are entered into an oral cavity and tooth rows are closed in position of central occlusion.

6. After  wax hardening, and checks of correctness of fixing of  bite height and central ratio of jaws, reference lines are put on the roller : a median line, a line of teeth closure, a line of canines, a smile line.

7. Wax templates are taken from an oral cavity.

Requirements for bite rollers after defining central occlusion:

1.      Bite rollers must adjoin to models densely.

2.     Bite rollers must be stuck reliably together among themselves.

3.      Bite rollers must fix reliably models in position central occlusion.

4.     On bite rollers reference lines must be accurately made: a median line, a line of teeth closure, a line of canines, a smile line.

 

Making wax templates with bite rollers at full absence of teeth

Materialsupport:

Plaster models , cast from functional impressions.

Wax  basic – 2 plates.

Dental spatula.

Electric spatula.

Indelible pencil.

Orthodontic wire 0.8 mm in diameter.

Methodologyofimplementation:

1. To cut off with a warm spatula a slice of wax from a plate, necessary on the size, according to model.

2. To moisten model with water.

3. To warm up the cut off plate of wax on the one side.

4. To put to model with the returot saturates side.

5. To press out model with fingers very precisely , beginning on the upper jaw from palate, and on the lower jaw – from tongue side and further outside.

6. To strengthen bases of an orthodontic wire in diameter of 0.8 mm the in length of 2 cm, having bent it on inside and under the form of alveolar processes, to warm up and dip into basis, having added the boiling.

7. To warm up the second wax plate and tightly roll in roller.

8. To attach received roller strictly on the center of an alveolar process on a wax template.

9. To mould roller to basis with boiling wax  , forming steep vestibular surfaces, adhering to the sizes: the height – 1,5 cm, width =1 cm

10. To make a roller surface  smooth, to form a slant in distal departments.

11. To cut off wax basis on corresponding borders.

12. To remove from model and to smooth down wax on borders.

 

Requirements forbite rollers:

1.     Borders of wax templates must correspond to borders of dental prostheses.

2.      Templates must adjoin to models densely.

3.     Wax roller must settle down strictly on the middle of an alveolar process, width in frontal area 0.8 – 1.0 mm, in lateral 1 – 1.5 cm.

Dentoalveolar system formation periods.

1st period — after a birth of the child the masticatory apparatus is a «toothless mouth», alveolar processes aren’t expressed, there are rudiments of deciduous and greater part of succedaneous teeth, a corner of the lower jaw is blunt (for newborns — 140 °).

The upper jaw is developed more than lower that is connected with differentiation of CNS(central nervous system), a brain skull in pre-natal development and the upper jaw are adnate with a skull (brain department). The lower jaw catches up in development upper that is promoted by muscular work at natural and correct artificial feeding.

2nd, the period — formation of a  deciduous bite (since 6 months till 6 years). At the age of 6 months or later at children the first teeth erupt .

Laws of teeth eruption :

1) terms of eruption;

2) paired relationship of eruption;

3) certain sequence of eruption. Comes to an end with eruption of deciduous teeth at 2,5 years (30 months).

Features of deciduous teeth structure.

The equator is located at a tooth neck, bluish color, tubers aren’t expressed, teeth  stand densely, in dentition each tooth has one antagonist.                                   

At 3,5 — 4 years  jaws start to grow intensively at the expense of development of follicles of succedaneous teeth that is shown in occurrence physiological diastems and diaereses, in parallel  erasability of tubers takes place, the bite slightly decreases and so-called «infantile prognathism»is compensated  to that promotes also poorly expressed tuber. Result  of tubers erasing is displacement of the lower jaw forward after that each tooth gets two antagonists.

3rd period of teeth change (since 6 years to 12) — to eruption all succedaneous teeth, except the eighth. During this period jawsgrow basically at width.

The maxillofacial area (system), as well as all bodies and organism ability to live, is under constant influence of external and internal factors on an extent, ontogenetic and phylogenetic development.

Among all biosocial laws of a human body the major is its integrity and interrelation between the form and function.

The form and function influence each other: form change causes respective function alteration, and, on the contrary, the changed function continuously influences morphology of bodies.

The form and function as two parties of uniform process together adapt to eternally changing environment.

An example of interrelation between morphology and function is the unity of evolution of form and content at various stages of development of dentoalveolar systems.

In clinic of orthopedic stomatology especially the great value has studying of a structure and functional features of maxillary bones, a temporo-mandibular joint, chewing and mimic muscles, and also parodentium fabrics. Therefore before to get down to research, diagnostics and replacement of defects of dentoalveolar system, it is necessary to supper on the anatomic-functional characteristic of the specified bodies.

Anatomic-physiological features of parodentium fabrics.

Parodentium is the name for fabrics located round a tooth, that is – an alveolus, a periodontium, (alveolus periosteum  and a fang) and a gum.

Tooth  has the general source of blood circulation (an interdental artery)with the mentioned fabrics , together with them carries out functions peculiar to it, and at tooth disease these fabrics are inevitably involved in pathological process.

Thus, parodentium — uniform system in which all elements are closely connected with each other not only from anatomic-functional, but also from the genetic point of view.

The alveolus is intended for fixing of a fang and is its bed. It is closely connected with tooth, is formed and changes throughout all human life depending on process eruption tooth, its existence or  destruction. Alveolus walls partially resolve to give deciduous to tooth possibility to erupt, and again is restored, covering a neck of an erupted crown.

The alveolus form not completely repeats the form of a root located in it in a kind of presence of the periodontal crack filled with a periodontium. This crack is narrow at a neck of tooth and gradually extends in a direction to a root upper (the width of a crack fluctuates from 0,2 to 0,25 mm). The periodontium is located in a crack between two firm formations and  performs a big variety of functions.

Periodontium structure.

The periodontium consists from connective-tissue collagenic fibres ending with Shar Pei fibres and penetrated by a dense network of nerves and vessels.

These fibres with one end grow into tooth cement, another — in a bone fabric of an alveolus walls.

The main mass of periodontium consists of fibrous connective tissue; between bunches of fibres there are the cracks filled with friable connective tissue.

According to function periodontium fibres have different direction. Their anatomic structure and an arrangement correspond to a direction of pressure and draft to which tooth at an operating time is exposed. Periodontium fibres in the direction are divided on 3 groups:

1. Cervical fibres are located horizontally at a tooth neck. These fibres partially intertwine with the fibres going from a gum, and especially from a gum papilla, and also with other fibres incorporating to periodontium of the next teeth. They form difficult interlacing in the field of interdental partitions and tightly cover necks of teeth.

These dense powerful bunches form a so-called circular ligament of tooth lig. circulare.

2. Dentoalveolar fibres are located between a neck of tooth and a root upper on all length of a root and have an inclined direction, and the place of growing of fibres in an alveolus wall is above a place of growing of its second end in tooth cement (from upper to down from an alveolus to cement.)

3. Upper fibres have too an inclined arrangement, but in the opposite direction: the lower end grows into an alveolus, and upper one — in tooth cement.

Periodontium functions:

1. The periodontium serves first of all for tooth fixing (due to above listed fibres).

2. The periodontium possesses also ability to transform loading (that is is the shock-absorber of chewing pressure) thanks to feature of structure of Shar Pei fibres. It is promoted by a dense network of blood vessels, the lymphatic cracks filled with interfabric liquid, makes the hydraulic system promoting amortization of pressure. The same role is carried out by a friable connecting fabric.

However it is necessary to recognize that the dominant role in perception and regulation of chewing pressure belongs to nervous system.

The perceiving nervous terminations signal about degree of chewing loading and through afferent system of a cerebral cortex and efferent system of nervous fibres  reflexively regulate force of chewing muscles contraction.

4. Plastic function is expressed that the periodontium possesses ability to form new fabric. Cementoblasts are contained in it  — the cages forming cement, and osteoblasts — the cages bordering a wall of an alveolus and producing a bone fabric.

5. The periodontium carries out a nutritious (trophic) role thanks to an abundance of the blood vessels penetrating a root cover. They get into it from marrowy spaces and haversian spaces : about a neck of tooth they anastomise with gum vessels. The periodontium feeds cement, an alveolus and partially (together with a pulp) a dentine

6. Sensitive (sensory) function of periodontium is carried out due to it is supplied with a considerable quantity of nervous bunches, fibres and textures. This wide network of nerves makes periodontium rather sensitive to perception of tactile, painful and other sensations and promotes regulation of functional loading of teeth.

Temporo-mandibular joint.

(articulatio temporo-mandibularis).

This joint provides articulation of the lower jaw with a temporal bone. Its complexity lays in its incongruence and presence of an intraarticulate disk (at other joints it isn’t present). It is complicated  in function as well. Because of it there are various movements on character: sliding, rotation. These movements can be made as on horizontal, that and on a vertical axis.

Both temporo-mandibular joints represent uniform kinematic system. Movements only on the one side are impossible, in any direction.

On articulate process of the lower jaw a pouch attachment line covers a neck, and behind it settles down more low, on a back, concave part (fovea articularis) and on a front convex (tuberculum articulare) — articular tubercle. The articulate pole is bent more in sagittal direction. On the average depth of a pole is 6-7 mm.

The surface of an articulate pole is covered with fibrous cartilage which to the back is stretched to fissura petrosguamosa, and to the front passes in fibrocartilage of articular tubercle.

Articular tubercle is situated in parallel articulate pole and has a shape of a roller considerably curved in sagittal direction.

At newborns articular tubercle is absent, and its appreciable development is observed with eruption period of deciduous teeth. Fully articular tubercle formes out age 6—7   due to development of chewing function.

It is considered  to be that at the adult the  articular tubercle surface is inclined to occlusive planes at an angle 33-35 °.

Articulate heads of the lower jaw look like ellipse-shaped rollers , whose long konvergent axes cross at a front line of an occipital aperture under a blunt, strongly varying corner (109 °—160 °). The frontupper surface of a head is covered with a cartilage and represents actually articulate surface.

Intraarticulate  disk is adnate along the edges with an articulate pouch also divides an articulate cavity into two floors: upper-forward and lower-back.

The lower surface of a disk adjoins to an articulate head, upper — to articular tubercle.

The disk corrects incongruence articulate surfaces and at closed jaws plays a role of the distributor of pressure on joint head.

To internal edge of a disk are attached tendon fibres of the upper bunch of an external wing-shaped muscle that specifies in a role of last at its displacement. The disk consists from coarse-fibered connective tissue.

The articulate pouch lasts from edges of an articulate surface of a temporal bone to a neck of an articulate head of the lower jaw and inosculate  with an articulate disk on its edge. The pouch attachment line  forms a circle on a temporal bone.

On the lower jaw articulate process the pouch attachment line  covers a neck, and behind it is more low. Bright demonstration of this position is existence of various forms of an articular tubercle: flat, medium-protuberate, abrupt. The first form develops at a direct bite, the second — at orthognathic, the third — at deep.

At rough food consumption powerful lateral motions of the lower jaw prevail; at the use of easily chewed food lateral motions are expressed in a minimum way.

In the first case articular tubercle disturbs lateral motions and doesn’t develop, – it well grows in the second (B.N.Bynin). But also after the bite will be generated, the joint continues to be in sphere of influence of function. For example, the joint of the person is compelled to adapt to new functional inquiries in connection with loss of molars.

At full loss of teeth in connection with change of amplitude of movements of the lower jaw, and also activity of chewing muscles the joint  reconstructs again, adapting for new conditions.

The big role is played by muscles in management of activity of a temporo-maxillary joint .

 External wing-shaped muscles which harmonious work together with an articulate disk and an articulate head is the precondition of normal function of a joint have a specific function.

Cartilage articulate disk, connected with an external wing-shaped muscle, coordinates and stabilizes movements of the lower jaw. Joint ligaments play only auxiliary role.

Teeth. Dentition.

Both upper, and lower tooth arches are formed by teeth of the various form (cutters, canines, premolars, molars). Their functions are various.

Lateral teeth, unlike cutters and canines, has the chewing surface supplied with tubers. On premolars there are two tubers — cheek and tongue, on molars — four:

two cheek and two tongue ones. An exception is lower first molar which chewing surface bears five tubers: three cheek and two tongue.

The form of lateral teeth is adapted for food chewing that’s why they are  called chewing.

Cutters and canines have one root each.  Premolars have root bifurcation, and lower big molars have two roots, upper —  three. It makes multiroot teeth more adapted for perception of the horizontal pressure developing during time of food grinding.

In practical stomatology at the description of teeth it is accepted to distinguish an anatomic and clinical crown.

As the first is called the part of tooth covered with enamel, the second — the part of an oak acting over a gum.

The anatomic crown as a result of deleting of tubers or cutting edge decreases with years, clinical — rather increases owing to an atrophy of a gum and a root exposure. It is considered to be that the length of a crown concerns length of a root, as 1:2. Measurements of length of a crown and roots have shown that this position is fair only for a special case, namely for upper molars and lower first premolars.

An upper row of succedaneous teeth is of semiellipse form, lower — parabolas. The upper dentition is wider than lower owing to what the upper foreteeth block the lower, and cheek tubers of the upper chewing teeth look out from the lower.

Such ratio of dentition increases possibility of chewing excursions of the lower jaw, expanding a useful area for crushing and food grindings.

The factors which provide stability dentition.

The unity of dentition is provided by interdental contacts, alveolar process and periodontium.

Interdental contact points at foreteeth are located near to cutting edge, and at lateral — near to a chewing surface. Under them the triangular space is turned with its basis to alveolar process.

The last is filled with interdental gum papilla which thus appears protected from being damaged by food.

Interdental contacts, providing morphological unity dentition, give them at chewing character of body.

The pressure falling on any tooth, extends not only along its roots on alveolar process, but on interdental contacts on the next teeth.

With the years contact points are erased and instead of them contact platforms are formed.

Erasing of contact points is the indirect demonstration of physiological mobility of the teeth made in three mutually perpendicular directions (vertical, transversal, sagittal).

The unity of dentition is provided by also periodontium and an alveolar process. The important role in communication between separate teeth is played by an interdental ligament of marginal periodontium. Thanks to this ligament movement of one tooth medially or distally causes movement of others by a number of standing near teeth, It theoretical position has been confirmed by experiments (D.A.Kalvelis).

Teeth of the lower jaw are inclined with crowns inside, and with roots outside. Cheek camber of a tooth arch, the form and position of teeth of the lower jaw create thus additional stability for the lower dentition.

Crowns of lower molars, besides, are inclined forward, and roots — backwards. This circumstance prevents dentition from shifting back.

Teeth of the upper jaw are inclined with crowns outside, and roots inside. Horizontally operating forces, arising at chewing, are able only to strengthen an inclination of a tooth which in process of its inclination outside more loses support of the next.

This feature of an arrangement of the teeth, doing the upper dentition less steady in comparison with lower, is compensated by a considerable quantity of roots at the upper chewing teeth.

The form of tooth arches, their teeth arrangement and character of their inclination have also specific features.

In orthopedic stomatology it is accepted to distinguish, except tooth, alveolar and basal arches. By alveolar an arch we mean a line spent on crests alveolar process. A basal arch passes on uppers of roots and is frequently called an apical basis.

As on the upper jaw crown roots inside are inclined outside, and, its tooth inside, arch is wider than alveolar one, and later is wider than basal one.

The basal arch, thus, is a place where chewing pressure concentrates and where buttresses originate.

On the lower jaw, on the contrary, owing to an inclination of crowns of teeth inside, and roots outside a tooth arch already alveolar, and later already basal.

For this reason with loss of teeth the lower jaw at its approach to the upper acts forward, creating visibility of progeniuses (senile progenius).

Articulationisevery possible positions and movings of the mandible in relation to the maxilla carried out by means of chewing muscles (A.Ya.Katts). Of greatest practical value is moving of the mandible in chewing.

     Occlusionis any joining of the teeth, a special case of articulation (A.Ya.Katts). The number of occlusion is great. The most important of them in practice are fourocclusions: centralocclusion, anterior and two lateral (left and right) occlusions.

     It is clear thatocclusion being clinical expression of the chewing movements, breaks up into separate phases according to kinds of the chewing movements. The chewing movements of the mandible as well as its general movements, are divided into sagittal, transversal and vertical. In this connection occlusion phases or phases of the dentitions should also be divided into sagittal (anteroposterior), transversal (lateral) and vertical (central). It coincides with division of the chewing process into three phases:

1) a phase of gripping and cutting of food which is characterized by sliding of the cutting edges of the lower anterior teeth along the palatine surfaces upward to their regional joining and backward; sagittal movement prevails in this phase and, hence, sagittalocclusion;

2)the phase of food crushing which is carried out by the vertical movement of the mandible and characterized by the maximal contact of the teeth of both jaws; occlusion of dentitions in this phase has received the name of central and is the initial and final moment of all chewing movements of the mandible;

3) a phase of grinding food which is characterized by alternating movings of the mandible to the sides. In movement of the mandible in any side the tubers of the masticatory teeth of the mandible will contact with same tubers of the maxilla (buccal with buccal, palatal with lingual) on this side.

     The word “articulation” is derived from anatomy where it designates a joint, articulation, however many authors give different meaning to this word. In our dentistry the definition of this term given by A.J.Kats is of the greatest use – articulation is every possible positions and movings of the mandible in relation to the maxilla carried out by means of the chewing muscles.

     This definition of articulation includes not only chewing movement of the mandiblebut also its movement during conversation, yawning, etc. For practical purposes it is most convenient to define articulation as a chain of variants of occlusion replacing each other. Such definition is more concrete, i.e. covers only chewing movements of the mandiblewhich studying is very important for construction of special devices reproducing them – articulators.

     Occlusion is joining of dentitions on the whole or by separate groups of the teeth during a greater or smaller interval of time.

     Thus, occlusion is considered to be a special case of articulation, one of its moments.

     Four basic kinds of occlusion are distinguished: central, anterior and lateral (right and left).

     Central occlusion is characterized by joining teeth at a maximum quantity of contacting points (Fig. 1).

     Signs of centralocclusion:

– the midline of the face coincides with a line passing between the central incisors;

– articular heads are located on the slope of the articular tubercle at its basis.

The front view and side view.

     There is simultaneous and uniform contraction of the masticatory and temporal muscles on either side.

     In the anterior occlusion there is a moving out of the mandibleforward. It is achieved by bilateral contraction of the lateral pterygoid muscles (Fig. 2).

Signs of anterior occlusion:

– The midline of the face coincides with the midline which passes between the incisors;

– The articular heads in anterior occlusion are displaced forward and located at the top of the articular tubercles.

     Lateral occlusion arises in moving of the mandibleto the right (right occlusion) or to the left (left occlusion) (Fig. 3).

Signs of lateral occlusion:

– in displacement of the mandible to the right the articular head remains at the basis of articular tubercle on the side of displacement, slightly rotating. On the left side the articular head is located at the top of the articulate tubercle;

– right lateral occlusion is accompanied by contraction of the lateral pterygoid muscles of the opposite (left) side and, on the contrary, left lateral occlusion – contraction of the same muscle of the right side.

Condition of relative rest of the mandible.

     If there is no chewing and talking dentition are usually opened, i.e. the mandiblehangs and a lumen of 1-6 mm in size is observed between frontal teeth. In dropping of the jaw the muscle are a little stretched that causes irritation of the proprioceptors.

 It necessitates tonic contraction of the muscles which keeps the jaw in the specified position. Various groups of fibres are alternatively contracted in the masticatory muscles that provides rest and at the same time allows to be ready to new contraction. Energy expenses of the muscles under the condition of relative physiological rest are minimal. The width of the lumen between the central incisors in position of rest of the mandibleis individually various. There are data that it increases with the years. Besides the position of relative rest of the mandibleis an expedient reflex act (an alternating masticatory pressure is physiological for the periodontium whereas constant rest would cause its ischemia and development of  dystrophy).

Position of the rest of the mandibleis a protective congenital reflex. It is initial and final for all its movements.

BIOMECHANICS OF THE MANDIBLE

     Biomechanics is a science about movements of the person and animals. It studies movements from the point of view of the laws of mechanics peculiar to all mechanical movements of the material bodies without exception. Biomechanics investigates the objective laws revealed during research. Their knowledge allows to expect results of practical activities, assisting in conduction it systematically counting upon the certain result.

     Studying of movements of the mandibleallows to receive representation about their norm as well as to reveal impairments and their influence on activity of the muscles, joints, teeth occlusion and condition of the parodont. The mandibleparticipates in many functions: chewing, speech, swallowing, laughter, etc. but its masticatory movements are of greatest value for orthopedic dentistry. Chewing can be made in high-grade only in case the teeth of the mandibleand maxilla come into contact (occlusion). Occlusion is the basic property of chewing movements. Other functions (speech, swallowing) are performed when dentitions are opened.

     The mandibleof the person makes movement in three directions:

– Vertical (upwards and downwards) that corresponds to opening and closing of the mouth;

– Sagittal (forward and backward);

– Transversal (to the right and to the left).

     Each movement of the mandibletakes place in simultaneous sliding and rotation of the articular heads.

Vertical movements of the mandible.Vertical movements correspond to opening and closing of the mouth and are made owing to alternate action of the muscles lowering and lifting of themandible.

     Lowering of the mandibleis performed by contraction of the digastric (anterior belly), mental-hypoglossal and mylohyoid muscles.

     In closing of the mouth lifting of themandibleis performed by contraction of the masticatory, temporal and medial pterygoid muscles.

     In opening of the mouth the articular heads slide along the slope of the articular tubercle downwards and forward.

     In maximal opening of the mouth the articular heads are established at the first line of the articular tuber. Thus various movements take place in different parts of the joint. In the upper part there is sliding of the disk together with the articular head downwards and forward, and in the lower part the articular head rotates in a deepening (recess) of the lower surface of the disk for which it is a mobile articular fossa.

     In opening of the mouth each tooth of the mandiblefalls downwards and, being displaced back, describes a concentric curve with a general centre in the articular head. As the mandiblefalls downwards and is displaced back, curves in space in opening of the mouth, the axis of rotation of the articular head will be displaced.

     The way passed by the articular head regarding the slope of the articular tubercle refers to as the articular pathway. The articular pathway represents not a regular curve but the broken line consisting of great number of curves.

     In various phases of movement of the mandiblethe centre of rotation will be displaced (by Gizie).

     Sagittal movements of themandible.Sagittal movements of themandibleare made by bilateral contraction of the lateral pterygoid muscles.

     Movement of the mandibleforward can be divided into two phases. In the first phase the disk together with the head of the mandibleslides along the articular surface of the tubercles. In the 2-nd phase sliding of the head is joined by its swivel movement around the transversal axis proper passing through the head.

     The distance which the articular head passes in movement of the mandibleforward is called sagittal articular pathway. The sagittal articular pathway is characterized by the certain angle (Fig.).It is formed by crossing of the line lying on continuation of the sagittal articular pathway with the occlusalplane. The angle of the sagittal articular pathway, according to Gizie, is on the average equal to 33°.

     The pathway made by the lower incisors in pushing of themandibleforward, refers to as sagittal incisor pathway. The angle is formed in crossing the line of sagittal incisor pathway with the occlusalplane which is called the angle of sagittal incisor pathway. According to Gizie it is on the average equal to 40-50°.

     In anterior occlusioncontacts in 3 points are possible:

– the 1-st is located on the anterior teeth;

– Two – on the distal tubersof the third molars.

     This phenomenon has received the name of Bonwill triangle

     Transversal movements of themandible.Lateral movements of the mandibleresult from unilateral contraction of the lateral pterygoid muscle. In movement to the right the left lateral pterygoid muscle is contracted, in displacement to the left – the right one.

     The articular head on one side rotates around the axis going almost vertically through the articular process of the mandible. Simultaneously the head of another side together with a disk slides along the articular surface of the tubercle. In movement of themandibleto the right, the articular head on the left side is displaced downwards and forward, and on the right side it rotates around the vertical axis.

     The articular head is displaced downward and forward and a little outside on the side of the contracted muscle. Its way is thus at the angle to the sagittal lines of the articular pathway. This angle was described for the first time by Benet and for this reason it is named by his name (the angle of the lateral articular pathway), on the average it is equal to 17°. On the opposite side the ascending ramus of the mandibleis displaced outside, thus standing at the angle to the initial position.

     Transversal movements are characterized by certain changes of occlusalcontacts of the teeth. As the mandible is displaced alternatively to the right and to the left, the teeth describe curves crossed at a blunt angle. The farther the tooth stands from the articular head, the blunter is the angle.

     Of significant interest are changes of mutual relations of the masticatory teeth in lateral excursions of the jaw. In lateral movements of the jaw it is accepted to distinguish two sides: working and balancing The teeth are positioned against each other by homonymous tubers on the working side, and on the balancing side – by heteronymic, i.e. the buccal lower tubers are positioned against palatal ones.

      In chewing of food the mandiblemakes a cycle of movements. Gizie has presented cyclicity of movements of the mandible in the form of the scheme given below.

1. The initial moment of movement is position of central occlusion

2. The jaw is lowered and pushed forward

3. The jaw is displaced aside (lateral movement) and the teeth join at the working side by homonymous and at the balancing one – by heteronymic tubers

4. The teeth come back in the position of central occlusionand the chewing cycle is repeated

Filing of complete dentures, adaptation to dentures. Processing of complete dentures after polymerization plastics, correction of complete dentures, denture repairs. Impact of prosthesis on oral tissues. Features re-prosthesis patients complete removable dentures.

         Dentures, also known as false teeth, are prosthetic devices constructed to replace missing teeth, and which are supported by surrounding soft and hard tissues of the oral cavity. Conventional dentures are removable, however there are many different denture designs, some which rely on bonding or clasping onto teeth or dental implants. There are two main categories of dentures, depending on whether they are used to replace missing teeth on the mandibular arch or the maxillary arch.

 Dentures can help patients through:

• Mastication as chewing ability is improved by replacing edentulous areas with denture teeth.
• Aesthetics because the presence of teeth provide a natural facial appearance, and wearing a denture to replace missing teeth provides support for the lips and cheeks and corrects the collapsed appearance that occurs after losing teeth.
• the improvement of pronunciation of those words containing sibilants or fricatives by replacing missing teeth, especially the anteriors enabling patients to speak better.
• improving self-esteem

Modern dentures are most often fabricated in a commercial dental laboratory using a combination of a tissue shaded powder polymethylmethacrylate acrylic (PMMA) for the tissue shaded aspect, and commercially produced acrylic teeth available in hundreds of shapes and tooth colors.

The process of fabricating a denture usually begins with a dental impression of the maxilla or mandible. This impression is used to create a stone model that represents the arch. A wax rim is fabricated to assist the dentist or denturist with establishing the vertical dimension of occlusion. After this a bite registration is created to marry the position of one arch to the other.

Once the relative position of each arch to the other is known, the wax rim can be used as a base to place the selected denture teeth in correct position. This arrangement of teeth is tried in the mouth so that adjustments can be made to the Occlusion. After the occlusion has been verified by the dentist with the patient, and all phonetic requirements are met, the denture is processed.

Processing a denture is usually performed in a lost-wax process whereby the form of the final denture, including the acrylic denture teeth, is invested in stone. This investment is then heated, and the wax is removed through a sprue when it melts. The remaining cavity is then either filled by forced injection or pouring of the uncured denture acrylic. After a curing period, the stone investment is removed, the acrylic is polished, and the denture is complete.

 

Whether some or all of the natural teeth are missing, there are several benefits from replacing them with complete or partial dentures. Replacing missing teeth helps to fill out the smile by giving support to the cheeks and lips. Also, a more youthful, vibrant appearance is achieved by supporting facial muscles. Speaking, chewing, swallowing and smiling are also improved. Partial dentures prevent teeth from shifting into the spaces created by the missing teeth. This helps prevent bite problems and decreases the likelihood of gum disease that is often associated with crooked teeth.

When a denture is attached to dental implants, especially the lower denture, its retention and stability are dramatically improved. Also, the bone loss that occurs yearly with complete dentures is avoided.

Stages of making complete removable dentures

Clinical stages

First visit

obtaining anatomical impressions (alginate material is usually used for making impressions ). Similar impressions are taken at partial defects of dentition

Second visit:

Obtaining functional impression (with thermoplastic or silicone mass). Is obtained by special samples

Third visit:

Determination of the central relationship of the jaws, the choice of form and color of teeth, prosthetic plane determination, drawing landmarks for setting the teeth

Fourth visit:

Check of  prosthesis structures in the mouth

Fifth visit:

Fitting the prosthesis to the patient jaw and its correction

Laboratory stages

 

 

1.                  Getting a model from plaster, defining the boundaries of the denture base and making an individual spoon

2.                  Production of a model(better use highly strong varieties of gypsum). Manufacture of wax patterns with bite rollers

3.                  Strengthening plaster models in an occludor or articulator, torus and exostosis isolation, setting artificial teeth in wax basis

4.                  Final modeling of a denture base, denture plastering in a flask, replacing wax on plastics, polymerization, grinding and polishing the prosthesis

5.                  The final polishing of prosthesis

 

Delivery of complete removable denture is a final stage of production of complete removable dentures.This is fixation, correction, adaptation processes and recommendations on the use of the denture. The main condition for the denture holding on toothless jaw is anatomical retention, functional suction – physical and biological methods for fixing dentures on toothless jaws. So making a functionally complete removable denture depends largely on  correctly obtained  functional impression, reasonable choice of impression mass , methods of   edge design of functional impression , wringing or unloading mucous membrane, prosthetic bed, etc.

Removable dentures are foreign body for a mouth and the patient, in addition, it inadequately conveys chewing load. So study the process of adjusting to it is very important.

Fixing complete romovable denture in the mouth is a responsible clinical moment. The procedure of entering complete romovable denture does not require any special efforts from a dentist- orthopaedist, but the next steps related to this, require special attention and patience.

The procedure of fixing finished complete romovable denture begins with a detailed review of them. Reviewing dentures is begun with detecting visible to the eye and those inequalities that are defined palpatorily, and are immediately removed  by a grinding method . After entering the prosthesis in the oral cavity it is checked whether the base does not fall  from  the prosthetic bed tissue and there are no balancing, and only then it is offered to the patient to close the teeth in position of the central relationship. Stability of dentures in upper jaw is checked by alternate manual finger pressing on the front and side teeth. The strength of locking valve in the field of soft palate is checked by folding back the cutting edges of upper teeth in lateral direction, on the lower jaw in the same way you assign the degree of base fixation in distal spots , in turns onthe right and left.

In addition, prosthesis fixation is checked by a patient himself, who performs set of movements of the mandible, mimic muscles and tongue. Basis of the prosthesis does not move from prosthetic bed during normal muscle contractions. While fixing the complete romovable denture lowering can be seen  or increase of intercollar height, fixing the central relationship of the jaws in lateral occlusion, but often mistakes are made in case of fixation of the central relationship of the jaws, when the patient pulls the lower jaw in front occlusion. In the absence of closure in the region of the frontal or side teeth such dentures need to be remade. Defined preliminary teeth contacts, areas of increased pressure within the denture base, and areas where muscles are excessively overlapping prosthesis, are removed by grinding-off. While fixing the prosthesis side and front-rear movements must be checked, artificial teeth, at which  the bite increases, particularly the canines must be grinded-off. Different actions are taken to keep maximum contact between the artificial teeth during movements. Front teeth, if they overlap considerably lower ones, are subjected to shortening.

Dentist-orsthopaedist after the above described manipulations should give the patient recommendations concerning the use of prostheses in the early days. Especially it should be done if the patient’s complete romovable dentures are made for the first time. Therefore it is necessary to emphasize that the prosthesis is a foreign body in oral cavity and it must be accepted this way. Often, after fixing the prosthesis a patient has a headache, nausea etc. In this case, it is recommended to withdraw dentures from the mouth. An important consideration during the use of prostheses is the first day. The patient is asked, if possible, during the first period  not to remove the dentures from the mouth even at night. Of course the doctor very easily achieves a proper fit of the denture base to prosthetic bed tissue, easy input and output from his mouth, but over time the patient comes to the doctor complaining that the prosthesis causes pain in certain areas where they have contact with mucous membrane.

      The elimination process places on the basis of the denture, which injures prosthetic bed tissue , is called a correction. Correction is conducted usually starting from the very next day after fixing dentures. The patient is asked to not use them in case of a pain, but about for 2-4 hours before visiting the doctor to enter the dentures in the mouth. Doctor during the review of oral mucous membrane easily determines the place of injury  prosthetic bed tissue  by edge of  denture base. Denture places, which cause injury, are grinded-off and polished.

      The number of corrections is different and can vary from one to ten. In the first period of prostheses use the patient must be supported  psychologically, noting that he already speaks the words that it becomes easier to eat ,that after a while all the discomfort disappears. The described  aspects of getting used to complete removable denture are called “adaptation””.

The term “adaptation” means adjustment, fitting. In terms of physiology orthopedic treatment of complete romovable dentures is a very serious interference in the human body and for the doctor to underestimate its complexity is unacceptable.

     Complex mechanisms of adaptation can be better understood if refer to classic works of I.P. Pavlov of braking process.

Complete romovable dentures are unusual stimulus, the patient experiences it as a foreign body. Patients often are obsessed with feelings of prosthesis and its location in the oral cavity, which prevents them from performing the work and fully relax.

In the first stage together with all the listed deficiencies salivation increases, indicating the first phase of adaptation, which is called reflex irritation, and goes from 1 to 3 days. The nature of this reflex is unconditional, it recalls the reaction caused by the action of substances which are not accepted by the body. Vomiting reflex is caused by mechanical stimulation of receptor root of the tongue or soft palate. This reflex has a protective character. During the first week using the prosthesis the mentioned reaction to the irritation begins to subside, foreign body sensation changes. Salivation decreases, vomiting reflex disappears. These signs indicate that second phase of adaptation starts, entitled conditioned inhibition and extended for one further week.Patient ceases to feel the presence of the denture in the mouth, forgets about it and feels uncomfortable only when the prosthesis should be removed from the mouth. The third phase of adaptation extends to 30-35 days and is called extinction of conditioned stimuli and habituation to complete romovable denture. Valuable criterion for assessing adaptation to complete romovable dentures is adaptation.

E.I. Gavrilov (1978) believes that doctors should monitor patients for as long as there is no sure of the full adaptation to the onset of complete romovable denture. These measures, he calls the principle of completeness of treatment.

     Often, doctors are asked the following question: whether to remove a prosthesis from oral cavity at night? If this question is not of only one person, then, in principle, dentures need to be removed from the mouth to decrease its staying on its mucosa. It is more difficult to solve this issue in relation to a particular patient. Before giving advice, the doctor must take into account the patient age, sex, marital status, as far as changing the aesthetic appearance of the patient in case of removing a prosthesis from an oral cavity. Especially it concerns younger patients, older patients in recommendations for removing a prosthesis from an oral cavity  at night does not cause psychological stress.

Patients are recommended to rinse their mouth with decoction of oak bark, weak Nitrofural solution (1:5 000), solution of potassium permanganate. Do not use baking soda because it leads to breaking mucosa, which in turn will facilitate the emergence of prosthetic stomatitis.                                    

               

Patient instruction in the care of the dentures should include the following topics:

• Denture insertion and removal
• Cleaning dentures
• Diet
• Night use
• Recall
• Use of denture adhesive

Denture Insertion

Denture insertion is seldom a topic requiring patient instruction at the insertion appointment. However, there are three possible exceptions to this rule:

• First-time denture wearers may want to know if it matters which prosthesis is inserted first. A patient asking about this should be reassured that the order of insertion does not matter—unless there is virtually no retention to the upper denture. In this case the lower plate should be inserted first.
• If the patient has significant undercuts in the retromylohyoid space, instruction should clarify the mandibular denture needs to be positioned posterior to its ultimate position; the posterior segment seated; and then the prosthesis brought anteriorly and then fully seated.
• If the patient suffers from cognitive dysfunction due to stroke or Alzheimer’s Disease (or other dementia), it may be impossible for him or her to initially distinguish upper and lower denture or to correctly position a prosthesis over the ridge. In such an event, the dentist needs to work with both the patient and the caregiver who will be able to reinforce the information away from the office. Parenthetically, it should be stressed that for some patients, use of a mirror will actually make the process MORE difficult, whereas it may ease matters for others.

A fourth situation meriting instruction on insertion occurs when the subject of denture adhesive is brought up, whether by the patient or the dentist. This will be covered in more detail shortly, in the section titled “Protocol for the Use of Denture Adhesive.”

Denture Removal

Patients with no prior familiarity to removing a denture should be instructed to break the seal by running one or both fingers along the full length of the flanges, or by puffing out the cheeks (making a “P!” sound).

Cleaning Dentures

 
Patients should be taught to remove their prostheses after each meal for a rinsing and to clean thoroughly at least once daily. Thorough cleaning involves brushing and soaking.

Brushes specifically designed for denture cleaning should be recommended. These feature a wide handle for easy gripping; stiff bristles of one length on one side of the head (for use against broader, flatter denture surfaces such as facial, palatal, and lingual surfaces); and bristles set in a pyramidal arrangement on the other side (for cleaning the tissue surface of the denture). Patients should be cautioned not to use toothpaste (other than toothpaste specifically designed for use on dentures) as the high abrasivity of non-denture toothpaste will scratch acrylic, thereby, dulling and removing anatomic and esthetic details from the denture surface.

Daily soaking in cleanser specifically designed for dentures is recommended for assuring cleanliness and eliminating odors. Patients should be cautioned to always rinse the denture thoroughly after soaking in order to avoid ingesting traces of caustic cleaning agents.

Diet

Patients should be cautioned that chewing and swallowing with the new dentures is a learned behavior and lip- and tongue-biting are very common risks at first. To ensure comfortable eating while fostering confidence in the prostheses, patients should be urged to continue to consume the quality and variety of foods they did prior to receiving the new dentures until those foods can be easily consumed without discomfort from the dentures. As a patient gains skill with the prostheses, the range of foods can gradually expanded to include crisp fruits cut in small pieces, nuts, and sandwiches.

• Continue former diet

Add new foods as comfort increase

Night Use

Patients, whether first-time users or those receiving a new set, should always be instructed to leave their dentures out of the mouth for at least 6 hours per day in order to allow the bearing tissues to rest. For most individuals, this is most conveniently and acceptably accomplished during sleep. Whenever dentures are removed for an hour or more, they should be thoroughly cleaned and then placed in water or a cleansing agent.

 

Recall

Patients with complete dentures likely have lower awareness of preventive dental behaviors than the average American consumer. As such, a deliberate, proactive effort must be made to bring them back to the practice annually for a recall. This is important to re-evaluate and revise, as necessary, the prostheses and to assess the health of the oral cavity. Over 90% of the 30,000 new cases of oral cancer diagnosed in America annually are found in persons over age 50 years. Denture use is correlated with advanced age, use of tobacco, and lower socioeconomic status—the three strongest risk factors for development of oral cancer. As such, it is essential for dental professionals to establish and stress a program of recall examinations for their edentulous patients just as they do for their patients who maintain their natural teeth.

The main condition for the maintenance of dentures on toothless jaw is their anatomical retention, functional suction – physical and biological method of fixation of prostheses on toothless jaws. So making a functionally complete   dentures depends largely on obtaining functional impression correctly,reasonable choice of  impression mass, methods of designing  edges of a  functional impression, streak or unloading mucosal prosthetic bed, etc.

Removable dentures are foreign body for the mouth and the patient, it also conveys inadequate chewing load. So study the process of adjusting to it is very important..

Processing of complete dentures.

After completion of plastics polymerization  and complete flask coolness its release of her dental pliers begins. Denture is taken out from the flask very carefully. First, take the lid and the bottom of the flask and pull entire unit with the pressing, and then gently release prosthesis of gypsum.Exemption from plaster denture does not cause the difficulties, if good insulation of  plaster model surface was done .

Eliminating inequalities, surface dissonances , residues of plastic on the surface basis  is carried with various instruments –  files,burins, abrasives, drills, burs. Edges of the prosthesis are formed in curves, keeping the thickness and boundaries. Particular attention is given to treatment of artificial teeth in their places of attachment to an artificial basis.

During prosthesis processing with grinding  wheel and another it is necessary  to continually moisten the surface, which is treated to prevent overheating and deformation of plastic.

Denture surface facing the oral mucous membrane, is treated very carefully, cutting off only visible remnants of plastic so as not to disrupt relief which must correspond to microrelief of mucosal prosthetic bed.

For polishing the denture base sandpaper is used with different grain size, which is firmly fixed in drill paperhold. grinding is started with rough grinding paper and finished with fine, getting their smooth surface.

Polishing is begun with the application of tapered felted folds , applying pumice mixed with water on the denture surface. After appearing smooth surface folds are replaced with rigid brush that allows to polish places difficult of access. For providing mirror shine on a surface  a soft brush from threads and chalk mixed with water or mineral oil is used. The surface of the prosthesis, facing to the mucosa, and artificial teeth are polished with soft brushes with little effort, to prevent abrasion of plastic and violations of relief form.

Denture repair.

Denture bases repair is necessary if:

1)basis cracks or complete fracture ,

2) partial or full fracture of an artificial tooth,

3) clamp failure ,

4) removal of an abutment tooth,

 5) replacing the removed artificial tooth with an artificial one.

Depending on the nature of the damage repair may be done by obtaining an impression with or without prosthesis. In the case when there is a crack or full fracture of the base and when it is not possible to make the prosthesis and stick together, do not get an impression. But if denture parts caot be composed or there is lack of some of them an impression must be obtained along with prosthesis parts . In the laboratory, after casting models or, as is said, “pouring”, the prosthesis parts are removed, their edges are grinded off, removing plastic from each end  2-3 mm ; grinding off is conducted with dental mills. On the boundary of the fracture surface is polished with files, burins and mills , giving roughness. Fragments are put on the model, the gap between the parts of the prosthesis is filled with wax and  basis simulation  is conducted.

After the simulation model is plastered by direct method in flask basis, the entire prosthesis is filled with liquid plaster, leaving open only part of the wax. having cast a contraform after crystallization of gypsum flask is opened and  wax is smelted with hot water. After cooling flask plastic preparation is made. For one correction on average 4.3 g polymer and 2 ml of monomer are needed. Before forming the plastic dough break lines are wiped with a monomer, the required number of plastic dough is imposed , covering its wet with cellophane, and pressing is done. After the control cellophane is removed, plastic residues are removed , if necessary,plastic dough is added and  final pressing is done. Having checked the flask fixation on a clasp it is dipped into the bowl with water and polymerization is done. After treating and polishing denture again isfixed in the mouth.

In the case when there is breakage or fracture of artificial teeth or clamps, when there is a need for clamps transfer to another place because of loss of abutment teeth the denture fining is done. Its essence is that an impression is obtained from the jaw with prosthesis put on it , and then  model is cast.The position of central occlusion is fixed with thwe help of  blocks from the warm wax. Model is plastered in occludor. The clamp full bending is done , and if necessary  setting an artificial tooth is conducted. Model is plastered in a flask and wax is replaced on  plastic by conventional methods.After the prosthesis is treated, polished, grinded and sent to a clinic for fitting and fixing.

Separately we will stiop at  denture bases fining with selfhardening  plastics. This method is widely used in clinical prosthodontics, but necessary to recall that the conditions of its application is to conduct polymerization in the apparatus under pressure to reduce residual monomer.

 Description of fining is to glue parts with  dichlorineethan denture glue, which is contained in complex of selfhardening plastics ‘Protacryl’ and ‘Redont’.

Parts of the prosthesis are placed along  the fracture line, having  glued them before and are kept in this position for 2-4 min.

On cemented prosthesis  plaster model (‘pidlytok’) is cast. having smeared prosthesis and plaster with vaseline , a contramodel is obtained with the new portion of densely mixed plaster. After, the prosthesis is removed from the model and broked through bonding line, the fracture is grinded each side for 1-2 mm, making the notch.

 Model and  contramodel are smeared with insulating varnish ‘Izokol’, then part of the prosthesis is placed on the model.

Plastic Fracture line is greased with monomer. Polymerization  should be in a special apparatus under pressure for 8-10 minutes. After machining, grinding and polishing dentures are passed on for fitting and fixing in the mouth.

         Complete removable dentures correction.

The places elimination process  on the basis of denture, which injure prosthetic bed  tissue, is called a correction. Correction is conducted usually starting from the very next day after fixing dentures. The patient is asked to not use them in case of a pain, but about for 2-4 hours to visit the doctor must enter the dentures in the mouth.

 Doctor during the review of oral mucous membrane easily determines the place of injury tissue prosthetic bed with edge ofdenture base  . Places of denture, which cause injury, must be grinded off and polished.

The number of corrections is different and can vary from one to ten.

 In the first period of prostheses for each visit the  patient must be supported psychologically, noting that he already speaks the words that it becomes easier to eat that after a while all the discomfort disappear.dough is prepared with selfhardening plastic, strewing powder in  monomer tu full, covering wuth glass pot on top to prevent weathering monomer.

 The process of maturation of plastic dough goes 3-5 minutes, depending on air temperature. 

         Denture stomatitis is a common oral mucosal lesion in the United States and Western Europe. Prevalence rates of 2.5-18.3% in adults aged 35-44 years or 65-74 years are reported, with a predominance in the latter age group.Although patient age and denture quality alone do not predispose individuals this mucosal condition, the odds of developing stomatitis, denture-related hyperplasia, and angular cheilitis are increased almost 3-fold in denture wearers. Studies indicate that correlations may exist with the amount of tissue coverage by a maxillary denture, vitamin A levels, smoking of cigarettes, and not removing dentures.

                It may be that you have very few symptoms at all but there are some things to watch out for. When you take your dentures out, the area underneath may be very red. It could be painful when you are putting your dentures in or taking them out. You may also find you have red sores at the corners of your lips or on the roof of your mouth. White patches can appear anywhere on the inside of your mouth. You will most likely have bad breath and your dentures will feel that they are irritating the skin more thaormal.

If you suspect you have denture stomatitis, visit your dentist. He will be able to recognize the symptoms and prescribe a suitable course of treatment. If it goes untreated, your mouth will become very sore and it can ultimately lead to poorly fitting dentures in the near future. It can also last for years if you do not notice it and get some treatment.

Pathophysiology

Mucosal factors have been implicated in the etiology of this condition, as have behavioral and manner-of-use factors in patients who wear complete dentures. In these patients, the nighttime wear of the prosthetic appliance is the most significant factor.

Although the dominant etiologic factor now appears to be fungal infection, other factors must be considered; these include the prosthetic device itself and also local and systemic factors in patients who are aging and edentulous. The extent of inflammation has been correlated with the presence of yeast colonizing the denture surface. Trauma has been shown to have a role in the production of basement membrane alterations involving expression of type IV collagen and laminin (alpha 1), thus indicating a possible relationship between these elements and denture stomatitis. Regarding the prosthesis-related factor, an allergy in the form of contact mucositis is suggested. This reaction may be related to the presence of resin monomers, hydroquinone peroxide, dimethyl-p -toluidine, or methacrylate in the denture. Furthermore, contact sensitivities such as this one are more common with cold or autocured resins than with heat-cured denture-base materials.

Candida species have been identified in most patients or in all patients, with Candida albicans being the predominant species isolated in addition to many other candidal species. Whether the organism is merely commensal in this situation remains an issue because of the frequency of such organisms in the general population; the role of this organism as the sole etiologic factor in denture stomatitis is unclear; however, the presence of candidal organisms within the overall biofilm lends credence to its role in the development and maintenance of denture stomatitis. The etiology is best considered multifactorial, with the prosthesis considered the prime etiologic factor. The character of biofilm communities of denture wearers, however, has been shown to be distinctive when compared with healthy non – denture-wearing individuals.

 

International

Denture stomatitis is a common oral mucosal lesion in Western Europe, Thailand, and Turkey.

Race

No racial predilection is recognized.

Sex

Sex-related frequencies differ among studies; therefore, no clear sex predilection is apparent.

Age

The disease is more common in elderly persons than in young persons because elderly persons are more likely to wear dentures and because their level of oral and denture hygiene is reduced. In addition, age-related chronic disease (eg, type 2 diabetes mellitus), iatrogenic drugs, and age-associated immunocompromise contribute to this risk level.

Denture stomatitis usually occurs in a patient who wears a complete maxillary denture or a partial denture. The presence of deteriorating temporary soft denture lining material and an improperly matched cleanser (which generally is the case) is associated with an increased presence of candidal organisms within the biofilm.

In almost all patients, the duration of the lesion is usually unknown because of its asymptomatic nature.

On rare occasions, patients may complain of slight bleeding and swelling in the involved area, as well as a burning sensation, a xerostomialike quality, or cacogeusia.

 

Although symptoms are uncommon, the clinical presentation of erythema and edema in the part of the palatal mucosa covered by the denture base is a diagnostic finding. Intense erythema is the most common finding. Note the image below.

A variably intense erythema distributed over the part of the mucosa covered by the denture base is diagnostic of denture stomatitis.

At times, an obvious fungal infection in the form of white surface colonies or plaques may be observed on the mucosal surface. Variably intense erythema, which may also be associated with scattered petechiae, is distributed over the mucosa covered by the base of the denture but not beyond. Palpation of the involved mucosa reveals no tenderness or tissue friability. The severity of denture stomatitis can vary (see Staging).

  Risk Factors

• Poor oral hygiene
• Dietary deficiencies and malnutrition
• Chronic systemic disease
• Immune deficiencies
• Poor denture
• Smoking
• Cancer therapies

Diagnostic Tests and Interpretation

The diagnosis relies on clinical symptoms and history. Testing is not routinely performed.
Lab

• Tzanck test of historic interest only; herpes simplex virus (HSV) culture
• Serologic test for syphilis
• CBC; cultures to determine secondary infection

Follow-Up and Special Considerations If not resolving in 7–14 days or getting worse, consider CBC.

Diagnostic Procedures/Other

• Biopsy if persistent/recurrent/suspicious
• Immunofluorescence is useful in the differential diagnostic between RAS and bullous skin diseases (3).

Pathological Findings Biopsy suspicious lesions or lesions that fail to heal or chronically recur to rule out oral or hematologic cancer or vasculitis.

 

Treatment

Treatment of stomatitis depends on the causative factors. If cause is allergic, identification removal of the agent is critical. For infectious causes, antibiotic or antifungal regiments. Steroidal anti-inflammatory drugs for systemic conditions with stomatitis manifestation. If the cause of stomatitis is due to medical treatment or cancer therapy, treatment needs to be more aggressive.

Medication (Drugs)

• Acetaminophen or ibuprofen for analgesia
• Steroids, colchicine, and cytotoxic drugs for Behçet disease
• 2% viscous lidocaine (Xylocaine) swish and spit for local discomfort
• Liquid diphenhydramine (Benadryl) by mouth or swish and spit, for allergic reactions
• Antibiotics for gangrenous stomatitis (penicillin and metronidazole are reasonable first-line agents; often start with IV)
• Antifungal ointment (e.g., nystatin [Mycostatin]) for candidiasis-complicating angular stomatitis
• For candidiasis: Nystatin oral suspension 400,000 units (4 mL) q.i.d. × 10 days; swish and swallow (1 mL q.i.d. for infants)
• Acyclovir 200–800 mg 5 times a day × 7–14 days for herpetic stomatitis
• Sucralfate (Carafate) suspension 1 tsp swish in mouth or place on ulcers q.i.d. (helpful)
• Topical 0.2% hyaluronic acid for recurrent aphthous ulcers
• “Miracle mouth rinses”: Various combinations of the preceding in equal parts; use swish and spit out q.i.d.:
• Maalox or Mylanta, diphenhydramine, lidocaine
• Maalox or Mylanta, diphenhydramine, Carafate
• Duke’s: Nystatin, diphenhydramine, hydrocortisone
• Chemical cauterization with silver nitrate for aphthous stomatitis (treatment can cause burning sensation)
• Contraindications: Allergy to specific medication
• Precautions: Toxic dose of topical lidocaine is uncertain, but likely only 25–33% of dose may have significant absorption from open ulcers or mucous membrane.
• Topical minocycline for aphthous stomatitis (4)
• Steroid oral rinses (see “General”) or topical preparations for aphthous ulcers (Kenalog in Orabase) or oral steroids injected into lesions for severe cases
• Thalidomide 20 mg 1–2× daily × 3–8 weeks in HIV-positive patients with nonhealing aphthous ulcers (extreme caution for birth defects)
• For prevention or reducing severity of mucositis with cancer treatments, these agents have some evidence of benefit: allopurinol, aloe vera, amifostine, cryotherapy, glutamine (IV), honey, keratinocyte growth factor, laser, and polymixin/tobramycin/amphotericin (PTA) antibiotic pastille/paste (5)

Additional Treatment

General Measures

• In most cases, treatment of symptoms only
• Severe cases may require parenteral fluids, particularly children.
• Good oral hygiene
• Topical anesthesia
• Analgesics
• Oral rinses such as half-strength hydrogen peroxide
• Smoking cessation
• Refit dentures; daytime wear only
• Avoid specific allergens.
• Replace vitamin deficiencies.
• Treat malnutrition if present.

 

Prognosis

• Herpetic: Self-limited, with resolution in 7–14 days
• Hand-foot-mouth disease: Same as for herpetic
• RAS: 7–14-day course per episode
• Vincent: May progress to fascial space infection with airway compromise or sepsis
• Nicotinic: Resolves with cessation of smoking
• Denture: Resolves with proper fitting, careful oral hygiene, and daytime-only denture wear
• Erythema multiforme: Resolution in 2–3 weeks
• Stevens-Johnson: Resolution in about 6 weeks with adequate supportive care
• Recurrent ulcerative: As the name implies, recurs over time, but the overall prognosis is good
• Recurrent scarifying: Occasional patients suffer continuous ulcers; others have recurrence with eventual scarring. The prognosis is otherwise good.
• Behçet disease may recur for several years. Overall prognosis is related to other aspects of the disease.
• Angular: After correction of mechanical problems, allergic disorders, and nutritional deficiencies, the prognosis is good.
• Gangrenous: The most serious stomatitis, requiring aggressive treatment with IV antibiotics and débridement to avoid death
• Scarlatina: The prognosis is related to other manifestations of the disease.
• Herpangina: 7–14-day course with total resolution
• Uremic: Depends on the underlying renal disease

Complications

• Recurrent scarifying stomatitis may result in intraoral scarring with restriction of oral mobility.
• Behçet disease may result in visual loss, pneumonia, colitis, vasculitis, large-artery aneurysms, thrombophlebitis, or encephalitis.
• Gangrenous stomatitis may lead to facial disfigurement and even death.
• Scarlet fever may result in cardiac disease.
• Herpetic stomatitis may be complicated by ocular or CNS involvement.

 

Processing of complete dentures.

After completion of plastics polymerization  and complete flask coolness its release of her dental pliers begins. Denture is taken out from the flask very carefully. First, take the lid and the bottom of the flask and pull entire unit with the pressing, and then gently release prosthesis of gypsum.Exemption from plaster denture does not cause the difficulties, if good insulation of  plaster model surface was done .

Eliminating inequalities, surface dissonances , residues of plastic on the surface basis  is carried with various instruments –  files,burins, abrasives, drills, burs. Edges of the prosthesis are formed in curves, keeping the thickness and boundaries. Particular attention is given to treatment of artificial teeth in their places of attachment to an artificial basis.

During prosthesis processing with grinding  wheel and another it is necessary  to continually moisten the surface, which is treated to prevent overheating and deformation of plastic.

Denture surface facing the oral mucous membrane, is treated very carefully, cutting off only visible remnants of plastic so as not to disrupt relief which must correspond to microrelief of mucosal prosthetic bed.

For polishing the denture base sandpaper is used with different grain size, which is firmly fixed in drill paperhold. grinding is started with rough grinding paper and finished with fine, getting their smooth surface.

Polishing is begun with the application of tapered felted folds , applying pumice mixed with water on the denture surface. After appearing smooth surface folds are replaced with rigid brush that allows to polish places difficult of access. For providing mirror shine on a surface  a soft brush from threads and chalk mixed with water or mineral oil is used. The surface of the prosthesis, facing to the mucosa, and artificial teeth are polished with soft brushes with little effort, to prevent abrasion of plastic and violations of relief form.

Denture repair.

Denture bases repair is necessary if:

1)basis cracks or complete fracture ,

2) partial or full fracture of an artificial tooth,

3) clamp failure ,

4) removal of an abutment tooth,

 5) replacing the removed artificial tooth with an artificial one.

 

Depending on the nature of the damage repair may be done by obtaining an impression with or without prosthesis. In the case when there is a crack or full fracture of the base and when it is not possible to make the prosthesis and stick together, do not get an impression. But if denture parts caot be composed or there is lack of some of them an impression must be obtained along with prosthesis parts . In the laboratory, after casting models or, as is said, “pouring”, the prosthesis parts are removed, their edges are grinded off, removing plastic from each end  2-3 mm ; grinding off is conducted with dental mills. On the boundary of the fracture surface is polished with files, burins and mills , giving roughness. Fragments are put on the model, the gap between the parts of the prosthesis is filled with wax and  basis simulation  is conducted.

After the simulation model is plastered by direct method in flask basis, the entire prosthesis is filled with liquid plaster, leaving open only part of the wax. having cast a contraform after crystallization of gypsum flask is opened and  wax is smelted with hot water. After cooling flask plastic preparation is made. For one correction on average 4.3 g polymer and 2 ml of monomer are needed. Before forming the plastic dough break lines are wiped with a monomer, the required number of plastic dough is imposed , covering its wet with cellophane, and pressing is done. After the control cellophane is removed, plastic residues are removed , if necessary,plastic dough is added and  final pressing is done. Having checked the flask fixation on a clasp it is dipped into the bowl with water and polymerization is done.

After treating and polishing denture again isfixed in the mouth.

In the case when there is breakage or fracture of artificial teeth or clamps, when there is a need for clamps transfer to another place because of loss of abutment teeth the denture fining is done. Its essence is that an impression is obtained from the jaw with prosthesis put on it , and then  model is cast.The position of central occlusion is fixed with thwe help of  blocks from the warm wax. Model is plastered in occludor. The clamp full bending is done , and if necessary  setting an artificial tooth is conducted. Model is plastered in a flask and wax is replaced on  plastic by conventional methods.After the prosthesis is treated, polished, grinded and sent to a clinic for fitting and fixing.

Separately we will stiop at  denture bases fining with selfhardening  plastics. This method is widely used in clinical prosthodontics, but necessary to recall that the conditions of its application is to conduct polymerization in the apparatus under pressure to reduce residual monomer.

 Description of fining is to glue parts with  dichlorineethan denture glue, which is contained in complex of selfhardening plastics ‘Protacryl’ and ‘Redont’.

Parts of the prosthesis are placed along  the fracture line, having  glued them before and are kept in this position for 2-4 min.

On cemented prosthesis  plaster model (‘pidlytok’) is cast. having smeared prosthesis and plaster with vaseline , a contramodel is obtained with the new portion of densely mixed plaster. After, the prosthesis is removed from the model and broked through bonding line, the fracture is grinded each side for 1-2 mm, making the notch.

 Model and  contramodel are smeared with insulating varnish ‘Izokol’, then part of the prosthesis is placed on the model.

Plastic dough is prepared with selfhardening plastic, strewing powder in  monomer tu full, covering wuth glass pot on top to prevent weathering monomer.

 The process of maturation of plastic dough goes 3-5 minutes, depending on air temperature.  Fracture line is greased with monomer. Polymerization  should be in a special apparatus under pressure for 8-10 minutes. After machining, grinding and polishing dentures are passed on for fitting and fixing in the mouth

.

 

Complete removable dentures correction.

The places elimination process  on the basis of denture, which injure prosthetic bed  tissue, is called a correction. Correction is conducted usually starting from the very next day after fixing dentures. The patient is asked to not use them in case of a pain, but about for 2-4 hours to visit the doctor must enter the dentures in the mouth.

 Doctor during the review of oral mucous membrane easily determines the place of injury tissue prosthetic bed with edge ofdenture base  . Places of denture, which cause injury, must be grinded off and polished.

The number of corrections is different and can vary from one to ten.

 In the first period of prostheses for each visit the  patient must be supported psychologically, noting that he already speaks the words that it becomes easier to eat that after a while all the discomfort disappear.

Model quality check

Attention is paid to their integrity: existence of splits, pores, cracks, signs of injury by technical spatula, blurriness of prosthetic bed lines or defects on its surface. If defects occur one should again take the functional impression and cast new models.

Setting teeth in articulator check:

Attention is paid to color, size, style of teeth, incisor overlap size . Numbers of  color, size and style teeth should correspond to preliminary record in production warrant.

Lower incisors overlap by upper ones should be in the range 1-2 mm. The upper front teeth  lie 2 / 3 outside the mid-alveolar crest, and 1 / 3 through its center. Lateral teeth should have fisur contact. All teeth must have two antagonists, except the first lower incisors and second molars in the maxilla.

Molars and premolars must be placed in the middle alveolar process adhering to interalveolar lines. Intensity of sagittal and transversal compensation occlusion curves are taken into account.

Existence of palatal contact and tongue bumps of chewing teeth from the inside are checked.

Attention is paid to modeling wax base, its edges extensionality,fit tightness to the model.

Wax structure of the future prosthesis in the mouth check:

Dentures are inserted into the mouth and the correct placement of the median line between the central incisor, which should coincide with the middle line of the face is controlled. When opening mouth slightly only  cutting edges of incisors must be visible and at a smile front teeth are viewed almost to the neck. Type of tooth should correspond to the face shape. Patients are offered to perform the speech test, during which the distance between the front teeth, upper and lower jaws should be about 5 mm. 

When checking the construction of dentures errors  made in defining the relationship of the central jaw can be revealed. They can be divided into 5 groups:

1)            incorrectdeterminationoffaciallowerpartheight(lowering or increasing);

With increased bite facial expression of the patient will look somewhat surprised, nasolabial and cheek folds will be smoothed, while speech test “knock” can be heard, tooth gap in front during the speech test will be less than 5 mm, gap (2-3 mm) in a state of physiological rest will be missing . This error is eliminated by the following. If the upper dentition is set correctly, and increase was due to lower teeth, the teeth should be removed from the lower base wax, a new roller should be made or basis with a bite roller be taken, upon which the central relationship of the jaws was established, and the height is redetermined. If the setting of upper teeth done wrongly (incorrect prosthetic plane), then bite rollers for an upper jaw are made. Then again, the central relationship of jaws is defined and teeth are set.
At height lowering of the facial bottom part, when the upper teeth are set correctly, a heated wax strip is imposed  on the lower dentition and redefinition of the central relationshipn of the jaws is made, bringing the height to normal.A new wax base with an occlusion roller can be made for a lower jaw. If the reason of the height lowering are the upper teeth, it is necessary to redefine the central relationship of the jaws using new upper and lower rollers.

2)            fixation of the mandible with a shift in the horizontal plane;

most common mistake in defining the central relationship of the jaws is the advancement of the lower jaw forward and fixing it in that position. During checking structure dentition prognathic relationship is found out , mainly bump closing of lateral teeth, gap between the front teeth, bite rise to a height of bumps. This error is eliminated by redefining the central relationship with a new occlusion platen in side of mandible, and a group of front teeth is left for control.

Displacement of the mandible backwards at determination of the central relationship of the jaws of possible with loose joints. When checking anterior relationship of dentition is detected, papulose closing of lateral teeth, bite raising on papulose height. Fault is eliminated, redefining jaw central relationship with a new bite roller on the lower jaw. However, it should be noted that this is not always possible, because often lower jaw isnotfixed in a certain position .
Checking the design of denture at displacement of the mandible to the right or left, you may find bump closure on the opposite side of the shift, bite increase, a shift of the centre of lower denture in the opposite direction, gap between  chewing teeth on the side of displacement. The error is possible to be corrected by redefining the jaw central relationship with a new lower bite roller.

 

3)                           errors caused by discharge or gapping of bite rollers to the prosthetic bed (of model);

These errors occur due to uneven squeezing bite rollers during fixation of the central relationship of the jaws. This may be not accurate fitting lower roller to the upper one, uneven heating of lower roller with a hot spatula, gap between wax base and a model. Often the result of such mistakes in the clinic is the lack of contact between the chewing teeth of one or both sides. It is defined by entering cold spatula between the chewing teeth . Meanwhile a spatula turn around its axis is made, and at the moment can be seen as wax bases closely gets adjacent to underlying tissues. Correcting the error is done by imposing heated wax plate  in the chewing teeth area and bite redefinition.

4)braced basis during jaw central fixing relationship of the  jaw: This may happen when occlusive rollers are not strengthened with arched wires or alveolar part of mandible is very narrow. It is seen during establishing such bases on the model  that they are not firmly adjacent to it. In the clinic this error becomes apparent in the form of increased bite with uneven and uncertain chewing teeth papulose contact, gaps in front teeth. A mistake is corrected by redefinition of the central relationship of the jaws with new rollers, often with hard bases.

4)             fixation jaw central relationship at shifting one of the wax bases.

For unfavorable anatomical conditions in the mouth (II degree of atrophy in the mandible and III degree of atrophy of the upper jaw) during fixation of the jaw central relationship a shift forward or back of lower or upper, which happens more often, wax bases with occlusion roller can occur.
Checking prosthesis design, you can see the same picture as in the fixation of the mandible not in the central but in the front or back relationship, which was described above. A mistake is corrected, conducting re-redefinition of the jaw central relationship with new rollers made on  hard bases.Further, on these hard plastic bases teeth are placed and prosthetic restoration is checked. Application of hard bases in this case is justified because they are stable on jaws, caot be deformed or displaced as wax ones.In all cases, when testing prosthesis design mistakes are revealed and corrected, a top model is obtained from an occludor or articulator and plastered in a new position.

After examination of the  denture design in a clinic, dentures wax compositions are sent into the dental laboratory for final  wax bases modelling and their replacement into plastic ones.

Fixing complete romovable denture in the mouth is a responsible clinical moment. The procedure of entering complete romovable denture does not require any special efforts from a dentist- orthopaedist, but the next steps related to this, require special attention and patience.

The procedure of fixing finished complete romovable denture begins with a detailed review of them. Reviewing dentures is begun with detecting visible to the eye and those inequalities that are defined palpatorily, and are immediately removed  by a grinding method . After entering the prosthesis in the oral cavity it is checked whether the base does not fall  from  the prosthetic bed tissue and there are no balancing, and only then it is offered to the patient to close the teeth in position of the central relationship. Stability of dentures in upper jaw is checked by alternate manual finger pressing on the front and side teeth. The strength of locking valve in the field of soft palate is checked by folding back the cutting edges of upper teeth in lateral direction, on the lower jaw in the same way you assign the degree of base fixation in distal spots , in turns onthe right and left.

In addition, prosthesis fixation is checked by a patient himself, who performs set of movements of the mandible, mimic muscles and tongue. Basis of the prosthesis does not move from prosthetic bed during normal muscle contractions. While fixing the complete romovable denture lowering can be seen  or increase of intercollar height, fixing the central relationship of the jaws in lateral occlusion, but often mistakes are made in case of fixation of the central relationship of the jaws, when the patient pulls the lower jaw in front occlusion. In the absence of closure in the region of the frontal or side teeth such dentures need to be remade. Defined preliminary teeth contacts, areas of increased pressure within the denture base, and areas where muscles are excessively overlapping prosthesis, are removed by grinding-off. While fixing the prosthesis side and front-rear movements must be checked, artificial teeth, at which  the bite increases, particularly the canines must be grinded-off. Different actions are taken to keep maximum contact between the artificial teeth during movements. Front teeth, if they overlap considerably lower ones, are subjected to shortening.

Dentist-orsthopaedist after the above described manipulations should give the patient recommendations concerning the use of prostheses in the early days. Especially it should be done if the patient’s complete romovable dentures are made for the first time. Therefore it is necessary to emphasize that the prosthesis is a foreign body in oral cavity and it must be accepted this way. Often, after fixing the prosthesis a patient has a headache, nausea etc. In this case, it is recommended to withdraw dentures from the mouth. An important consideration during the use of prostheses is the first day. The patient is asked, if possible, during the first period  not to remove the dentures from the mouth even at night. Of course the doctor very easily achieves a proper fit of the denture base to prosthetic bed tissue, easy input and output from his mouth, but over time the patient comes to the doctor complaining that the prosthesis causes pain in certain areas where they have contact with mucous membrane.

      The elimination process places on the basis of the denture, which injures prosthetic bed tissue , is called a correction. Correction is conducted usually starting from the very next day after fixing dentures. The patient is asked to not use them in case of a pain, but about for 2-4 hours before visiting the doctor to enter the dentures in the mouth. Doctor during the review of oral mucous membrane easily determines the place of injury  prosthetic bed tissue  by edge of  denture base. Denture places, which cause injury, are grinded-off and polished.

      The number of corrections is different and can vary from one to ten. In the first period of prostheses use the patient must be supported  psychologically, noting that he already speaks the words that it becomes easier to eat ,that after a while all the discomfort disappears. The described  aspects of getting used to complete removable denture are called “adaptation””.

The term “adaptation” means adjustment, fitting. In terms of physiology orthopedic treatment of complete romovable dentures is a very serious interference in the human body and for the doctor to underestimate its complexity is unacceptable.

     Complex mechanisms of adaptation can be better understood if refer to classic works of I.P. Pavlov of braking process.

Complete romovable dentures are unusual stimulus, the patient experiences it as a foreign body. Patients often are obsessed with feelings of prosthesis and its location in the oral cavity, which prevents them from performing the work and fully relax.

In the first stage together with all the listed deficiencies salivation increases, indicating the first phase of adaptation, which is called reflex irritation, and goes from 1 to 3 days. The nature of this reflex is unconditional, it recalls the reaction caused by the action of substances which are not accepted by the body. Vomiting reflex is caused by mechanical stimulation of receptor root of the tongue or soft palate. This reflex has a protective character. During the first week using the prosthesis the mentioned reaction to the irritation begins to subside, foreign body sensation changes. Salivation decreases, vomiting reflex disappears. These signs indicate that second phase of adaptation starts, entitled conditioned inhibition and extended for one further week.Patient ceases to feel the presence of the denture in the mouth, forgets about it and feels uncomfortable only when the prosthesis should be removed from the mouth. The third phase of adaptation extends to 30-35 days and is called extinction of conditioned stimuli and habituation to complete romovable denture. Valuable criterion for assessing adaptation to complete romovable dentures is adaptation.

E.I. Gavrilov (1978) believes that doctors should monitor patients for as long as there is no sure of the full adaptation to the onset of complete romovable denture. These measures, he calls the principle of completeness of treatment.

         Often, doctors are asked the following question: whether to remove a prosthesis from oral cavity at night? If this question is not of only one person, then, in principle, dentures need to be removed from the mouth to decrease its staying on its mucosa. It is more difficult to solve this issue in relation to a particular patient. Before giving advice, the doctor must take into account the patient age, sex, marital status, as far as changing the aesthetic appearance of the patient in case of removing a prosthesis from an oral cavity. Especially it concerns younger patients, older patients in recommendations for removing a prosthesis from an oral cavity  at night does not cause psychological stress.

Patients are recommended to rinse their mouth with decoction of oak bark, weak Nitrofural solution (1:5 000), solution of potassium permanganate. Do not use baking soda because it leads to breaking mucosa, which in turn will facilitate the emergence of prosthetic stomatitis.                                    

               

The reaction of skin and oral mucosa at a dental laboratory plastics.

Used in dental practice materials inevitably lead to anti-living tissues and systems of the human body with allogenic materials. This ‘confrontation’ is represented most vividly in the mouth.

Dental materials have on living tissues of the human organism a direct  or indirect (through ‘mediator’) effect. Healthy tissues are in dynamic equilibrium with balanced biochemical processes that keep tissues and structures and support their function. Allogenic material breaks this balance, causing in the tissues of humans  different reactions, which tasks to eliminate these violations. These materials can in principle be toxic, allergens, carcinogens, mutagens, teratogenic. Under the influence of a strong irritant   human body tissue reacts on the basis of nonspecific inflammation, ie normergic reaction, characterized by the classic symptoms: redness, swelling, fever, pain. In people who use dentures these signs occur rarely, but can be seen under a microscope. Virtually every field has a prosthetic signs ‘struggle’ with alien body. Normergic reaction manifests itself when the intensity of hazards than tissue tolerant ability (endurance) .During minor irritation of living tissue structures remain. Strong irritation causes destruction, destruction of tissue.

  Description of the allergic reaction is the body or tissue of a living organism with appropriate sensitivity in contact with certain substances – antigen – antibody forming cells or sensitive.Repeated contact with antigen allergic reaction occurs.

Dental materials and their components are inferior antigens – so-called haptenes that can transform into a full-antigens resulting in connection with its own protein and have the ability to sensitization (sensitivity). Last is the background depends on the material dosage. First stage allergy can be compared with barrels, which gradually filled with water and suddenly overfills.

Plastic for making dentures

 Acrylic plastic has been used for dentures for 30 years. In recent years have been developed a variety of materials – filled plastic materials based on diacrylic.

Toxicological aspects

 Methyl  ether of methacrylic acid – monomer – is poison. What, however, its toxic properties are only at high doses. For skin monomer is a strong irritant, which inhibits the protective barriers quickly, with prolonged exposure to integuments appear first contact eczema of eealergic type, then – allergic contact eczema.

Polymethylmethacrylate with toxicological point of view is not dangerous even if not achieved 100% polymerization and plastic is very little residual monomer.however long known that components of dental dental materials can cause as stomatopathy in patients and allergic contact eczema skin hand techniques. It is in these cases of allergic risk.

Allergic aspects

When suspecting allergies clinical examination and the application skin test are usually conducted. Predict allergens to which the patient or dental technician can answer the reaction of the relevant parts of the body are used. The following situations:

1. Sensitization of skin only.

2. Sensitization of skin and mucous membranes.

3. Sensitization of only mucosa.

 Acrylic dentures while using absorb water, which contributes to destruction of plastics, inner tension appearance and pores lighting [15].Hardness and porosity, and poor care for dentures facilitate penetration of microorganisms in the oral cavity and lighting bases on its surface plaque, which contains carbohydrates, proteins, desquamated epithelial cells, leucocytes and others. Dentures are covered by dental plaque, the remains of food, epithelium desquamated cells .Most  often food debris are under the bases of removable plate prostheses on upper jaw. As a result, favorable conditions for living fungi, especially the genus Candida albicans. Microorganisms plaque, disposal and recycling of food carbohydrates, create a critical pH value in the retention points[6].   

How points Z.S. Vasilenko [3], the roughness as far various sizes, hills, spikes, sharp ridges, rough inner surface of the bases found in 25% plate dentures. Research by J.F. Roulet [21] showed that the inner surface of such features are present in 74% of the bases of removable plate prostheses . During use quite often inflammatory infectious process takes place, as well as dentures and mucous membrane prosthetic bed (nozzle) get contaminated by microbial flora. Representatives of the microflora of saliva V.A. Khramov and L.M. Gavrikova [14] divided into two antagonist groups: 1 – producers of urease (ureolitical), causing saliva increase by hydrolysis of urea and ammonia lighting. 2 – organisms that contain a set of glycolytic enzymes, which displace pH of saliva in the sour side fermenting sugar to organic acids..

Microbiological, biochemical and structural studies of plaque on removable dentures showed that it (denture plaque)is similar to the plaque on the surface of natural teeth. Essential for bacterial adhesion to different surfaces of prosthetic materials is the presence of free surface energy, and display them hydrophobic forces [16]. Some research shows that in acidic medium the decrease of metabolic activity by plaque buildup in its liquid phase acid anions with high pH (acetic, propionic, oil), which act as effective buffers in the product stronger acids (eg, dairy) plaque microorganisms. Metabolic products Candida albicans (lactic acid, etc.) can cause pain in the prosthetic bed, burning [22].

V.A. Levkin [8] notes that patients who do not remove the dentures at night or keep them dry at night, most often suffer from acrylic stomatithis. People, who do not remove dentures at night, have the number of colonies of fungus Candida albicans is 10 times higher than patients who use dentures only during the daytime. J. Kraft and co-authors [18] in studies in vitro have shown that using the tools that improve the adhesion of dentures on the mucosa, is an increase in the number of colonies Sandida spesies.

With prolonged use of dentures microorganisms can penetrate the thick plastic to a depth of 2 – 2.5 mm. Among modern acrylate highest permeability for microorganisms has plastic “Etakril”. All are acrylic plastic on the surface of white coating, changed in color, with time and age is depot for oral cavity.It was found that strains of the genus Pseudomonos Aerobacter aerogenose  destroy plasticizers that are part of the plastic, causing their collapse, which significantly worsens the basis material properties.Increase of microorganisms leads to increased enzymatic processes, contributing to the intoxication of the body.Irritating action of bacterial toxins cause unpleasant subjective sensation, hyperemia of the mucosa, so-called “effect bloodsicking banks”