Home » Filing of complete dentures, adaptation to dentures

Filing of complete dentures, adaptation to dentures

June 25, 2024

Fixation, stabilization and balance of complete dentures. Fitting rigid individual spoons. Getting functional imprints of the upper and lower jaws.

A Complete Denture are prosthetics devices constructed to replace missing teeth; they are supported by the surrounding soft and hard tissues of the oral cavity.

Fixation and stabilization of a complete dentures is the principle that describes how well the underlying mucosa (oral tissues, including gums) keeps the denture from moving vertically towards the arch in question during chewing, and thus being excessively depressed and moving deeper into the arch, making the patient feel comfortable.

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Indications for a Complete Denture

1.Lack of financial resources for alternative treatments.

2. Patient refused partial dentures.

3. Edentulous patient.

4. Gross decay or abscesses.

5. Lack of motivation or ability to maintain teeth.

6. Extensive bone loss and periodontal disease

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For edentulous patients, successful denture therapy is influenced by the biomechanical phenomena of support, stability, and retention Retention, or the resistance to movement of the denture away from the supporting tissues, is critical. Unfortunately, the physical, physiologic, and mechanical factors associated with denture retention are not completely understood. Physical forces influencing denture retention are believed to include adhesion, cohesion, capillary attraction, surface tension, fluid viscosity, atmospheric pressure, and external forces imparted to the prostheses by oral-facial musculature. Of these, interfacial surface tension associated with the saliva layer between the denture base and supporting soft tissues is quite important. This is particularly true for maxillary prostheses. Retention is realized as this saliva layer maximizes contact with approximating prosthetic and mucosal surfaces. Therefore, xerostomic patients who experience a quantitative or qualitative reduction in saliva may have reduced complete denture retention due to decreased interfacial surface tension

In the maxilla, alveolar resorption may obscure anatomic landmarks required to identify an effective postpalatal seal area. An ineffective or improperly located postpalatal seal may compromise denture retention. Therefore, reduced vertical alveolar height in a severely atrophic edentulous maxilla may result in poor denture stability and inadequate denture retention.

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The typical pattern of residual ridge resorption results in the medial-lateral and anterior-posterior narrowing the maxillary denture foundation and a perceived widening of the mandibular denture foundation. Resultant changes in horizontal maxillomandibular ridge crest relationships may necessitate setting posterior denture teeth in cross-bite. This arrangement may complicate force distribution to the denture bearing tissues. If cross-bite posterior denture occlusion is not carefully developed and managed in patients with severe residual ridge resorption, denture instability may result

The objective of complete denture therapy for patients with severe reduction of residual ridges is not solely the replacement of missing teeth. Rather, complete dentures must be designed to replace both the missing dentition and associated supporting tissues. In doing so, the denture base may occupy a substantial volume. Since denture base coverage of the hard palate is necessary to satisfy mechanical requirements of the prosthesis, and not to replace missing anatomic structures, care must be taken to limit denture base thickness in this area. In addition to replacing missing oral tissues, complete dentures structurally redefine potential spaces within the oral cavity. Inappropriate denture tooth positioning and physiologically unacceptable denture base contour or volume may result in compromised phonetics, inefficient tongue posture and function, and hyperactive gagging. Carefully designed external denture contours (i.e., cameo or polished denture surfaces) may contribute substantially to prosthesis stability and retention. Successful denture wearers master patterns of oral-facial muscular activity that serve to retain, rather than displace, their prostheses. When optimally contoured, complete dentures occupy space in the oral cavity defined by the physiologic limits of acceptable muscular function, thus acquiring stability and retention during mastication, deglutition, and phonation. Conversely, poorly designed prostheses that do not accommodate anticipated muscular function may yield compromised denture stability and reduced retention.

Complete denture retention is, in part, influenced by denture occlusion. Most denture wearers consciously or subconsciously perform random, empty-mouth occlusal contacts throughout the day. These contacts may result from functional activity (e.g., swallowing) or parafunction (e.g., bruxism or clenching). A bilaterally balanced denture occlusion in intended to minimize the adverse consequences of functional and parafunctional empty-mouth loading by widely distributing these forces to the denture bearing structures. Therefore, a properly balanced denture occlusion may serve to dampen potentially detrimental occlusal forces acting to disrupt denture stability. A balanced occlusion is dependent on effective clinical and laboratory procedures. Accurate and precise registration of maxillomandibular relationships, meticulous articulation of master casts, careful positioning of denture teeth, and correct processing of denture bases must be accomplished. Both laboratory and clinical remount procedures are essential if optimal occlusal balance is to be achieved prior to delivery of the prostheses. Finally, periodic recall of all edentulous patients allows reevaluation of the denture occlusion; a clinical remount can be performed when correction is indicated.

Complete maxillary and mandibular dentures have long been considered the standard of care for treating edentulous patients. While most edentulous patients express relative satisfaction with their maxillary complete dentures, many do not enjoy equally successful mandibular denture comfort and functionThe use of endosseous dental implants to assist in the support, stability, and retention of removable prostheses is now considered an effective treatment modality for the edentulous patient. Individuals wearing implant-assisted overdentures typically report improved oral comfort and function when compared to conventional, mucosa-supported prostheses. Except when contraindicated due to financial or surgical considerations, implant-assisted overdentures are usually the treatment of choice. A symposium held at McGill University addressed the efficacy of implant-assisted overdentures for treatment of edentulism. After thorough review of existing information, the following consensus statement was formulated:

FIXATION

This is the principle that describes how well the underlying mucosa (oral tissues, including gums) keeps the denture from moving vertically towards the arch in question during chewing, and thus being excessively depressed and moving deeper into the arch.

For the mandibular arch, this function is provided primarily by the buccal shelf, a region extending laterally from the back or posterior ridges, and by the pear-shaped pad (the most posterior area of keratinized gingival formed by the scaring down of the retro-molar papilla after the extraction of the last molar tooth). Secondary support for the complete mandibular denture is provided by the alveolar ridge crest.

The maxillary arch receives primary support from the horizontal hard palate and the posterior alveolar ridge crest. The larger the denture flanges (that part of the denture that extends into the vestibule), the better the stability (another parameter to assess fit of a complete denture). Long flanges beyond the functional depth of the sulcus are a common error in denture construction, often (but not always) leading to movement in function, and ulcerations (denture sore spots).

STABILIZATION

Stability is the principle that describes how well the denture base is prevented from moving in a horizontal plane, and thus sliding from side to side or front to back. The more the denture base (pink material) is in smooth and continuous contact with the edentulous ridge (the hill upon which the teeth used to reside, but now only residual alveolar bone with overlying mucosa), the better the stability. Of course, the higher and broader the ridge, the better the stability will be, but this is usually a result of patient anatomy, barring surgical intervention (bone grafts, etc.).

BALANCE

Balance is the principle that describes how well the denture is prevented from moving vertically in the opposite direction of insertion. The better the topographical mimicry of the intaglio (interior) surface of the denture base to the surface of the underlying mucosa, the better the retention will be (in complete dentures), the clasps are a major provider of retention), as surface tension, suction and friction will aid in keeping the denture base from breaking intimate contact with the mucosal surface.

It is important to note that the most critical element in the retentive design of a maxillary complete denture is a complete and total border seal (complete peripheral seal) in order to achieve ‘suction’.

The border seal is composed of the edges of the anterior and lateral aspects and the posterior palatal seal. The posterior palatal seal design is accomplished by covering the entire hard palate and extending not beyond the soft palate and ending 1–2 mm from the vibrating line.

Implant technology can vastly improve the patient’s denture-wearing experience by increasing stability and preventing bone from wearing away. Implants can also aid retention. Instead of merely placing the implants to serve as blocking mechanism against the denture’s pushing on the alveolar bone, small retentive appliances can be attached to the implants that can then snap into a modified denture base to allow for tremendously increased retention. Available options include a metal “Harder bar” or precision balls attachments.

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 on the right and left.

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.

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.

FITTING RIGID INDIVIDUAL SPOONS

Physiologically, teeth provide for greater chewing ability. They allow us to masticate food thoroughly, increasing the surface area necessary to allow for the enzymes present in the saliva, as well as in the stomach and intestines, to digest our food. Chewing also allows food to be prepared into small boli that are more readily swallowed than haphazard chunks of considerable size. For those who are even partially edentulous, it may become extremely difficult to chew food efficiently enough to swallow comfortably, although this is entirely dependent upon which teeth are lost. When an individual loses enough posterior teeth to make it difficult to chew, he or she may need to cut their food into very small pieces and learn how to make use of their anterior teeth to chew. If enough posterior teeth are missing, this will not only affect their chewing abilities, but also their occlusion; posterior teeth, in a mutually protected occlusion, help to protect the anterior teeth and the vertical dimension of occlusion and, when missing, the anterior teeth begin to bear a greater amount of force for which they are structurally prepared. Thus, loss of posterior teeth will cause the anterior teeth to splay. This can be prevented by obtaining dental prostheses, such as removable partial dentures, bridges or implant-supported crowns. In addition to reestablishing a protected occlusion, these prostheses can greatly improve one’s chewing abilities.

As a consequence of a lack of certaiutrition due to altered eating habits, various health problems can occur, from the mild to the extreme. Lack of certain vitamins (A, E and C) and low levels of riboflavin and thiamin can produce a variety of conditions, ranging from constipation, weight loss, arthritis and rheumatism. There are more serious conditions such as heart disease and Parkinson’s disease and even to the extreme, certain types of Cancer. Treatments include changing approaches to eating such as cutting food in advance to make eating easier and less likely to avoid as well as consumer health products such as multivitamins and multi-minerals specifically designed to support the nutritional issues experienced by denture wearers.

Numerous studies linking edentulous with instances of disease and medical conditions have been reported. In a cross-sectional study, Hamasha and others found significant differences between edentulous and dentate individuals with respect to rates of atherosclerotic vascular disease, heart failure, ischemic heart disease and joint disease.

Cause

The etiology, or cause of edentulism, can be multifaceted. While the extraction of non-restorable or non-strategic teeth by a dentist does contribute to edentulism, the predominant cause of tooth loss in developed countries is periodontal disease. While the teeth may remain completely decay-free, the bone surrounding and providing support to the teeth may reabsorb and disappear, giving rise to tooth mobility and eventual tooth loss. In the photo at right, tooth #21 (the lower left first premolar, to the right of #22, the lower left canine) exhibits 50% bone loss, presenting with a distal horizontal defect and a mesial vertical defect. Tooth #22 exhibits roughly 30% bone loss.

Individual spoon manufacturing from standard basis plates.

№ b\o	Steps of work	Methodic	Elements of Self-control
1.	Casted by anatomic cast plaster model	To paint the border of spoon by chemic pencil.	By a transitive cord bypassing bridles of cheeks, lips, tongue, capturing the tubers and retomolar tubers of lower jaw and passing on the palate on 2 mm distally for line “A”
2.	Standard plate AKR-P, spirit-lamp, spatula.	To heat the plate above the flame to a uniform ramollissement, to press out it on the model.	To watch for accuracy of adhering. At its lack repeat the heating and press out a plate.
3.	Chemical pencil.	To transfer the border on the pressed out plate surface.	Watching out for accuracy.
4.	Scissors, bohr-machine, fissure’s bohr, milling cutter.	To correct the border of spoon on the marking by a bohr-machine.	To achieve accuracy coincidence of spoon border with a mark on a model.
5.	The wire, crampon forceps.	To bend a handle from the orthodontic wire or the writing paper clip. For this should to bend the clip half-and-half and unbend the extremities on the alveolar process way.	Height of handle should to be 1 – 1,5 sm. The extremities should to disperse on the direction of alveolar crest.
6.	Spirit-lamp, crampon forceps.	To strength a handle to the spoon. Holding it by crampons to heat the unbend extremities and immerse in the plate.	The handle should to be strengthen under the angle of 45^• to the spoon plane and extruded in the mesial way.

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/.

For upper jaw.

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.

For lowerjaw.

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.).

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

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.

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

Facebow Record

Relates Maxilla to Transverse Hinge Axis

Determine Occlusal Vertical Dimension

Facial Height/Separation of Dentures

Centric Relation Registration

Ant/Post & Mediolateral Relationships

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

Box Impression

Stronger cast with peripheries for Processing

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.

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.

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

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 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.

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 patientsor 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.

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

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.:

o Maalox or Mylanta, diphenhydramine, lidocaine

o Maalox or Mylanta, diphenhydramine, Carafate

o 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.

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 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.

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.

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.

Complete removable dentures correction.

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

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) incorrect determination of facial lower part height (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.

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

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.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.

How points Z.S. Vasilenko , 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 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 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 . 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 .

V.A. Levkin 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 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”