Prepearing 

Prepearing cavities I-V classes in temporary and permanent teeth with immature roots. Selection of instruments.

 

The principles of cavity preparation

The clinical form of cavity preparation:

The principles of modern cavity preparation were first defined in 1896 by Dr. G.V. Black, a man considered by many to be the “father of modernrestorative dentistry”. When his original sequence of cavity preparation wasdescribed, “extension for prevention” of recurrent decay was one of the mostimportant considerations of cavity design. However, the degree of cavityextension is considerably less today, because of the realization that caries, primary or secondary, can be more effectively controlled and prevented bygreater emphasis on oral hygiene by the patient.Although techniques have been refined and outlines have beenmodified, Black’s Principles are still used as the basic steps in the process of designing and preparing a cavity. The adherence to these principles willfacilitate the procedure of cavity preparation and decay removal.Thus, this systematic approach is still recommended to the operativedentist as reliable guidelines for today.

The depth of the carious process has no effect on the general principles of preparation of the cavities. Features of the oral preparation is determined by its localization. The most valuable from a practical point of view, the proposed classification of cavities J. Blake. Classification used by dentists Black all over the world, and he proposed the principles of preparation of cavities in various modifications are the basis of the modern concept of preparation and undergo only minor changes in the emergence of new filling materials and features of their application.

Classification of lesions than the somewhat similar to writing an essay. According to the classification of Blake, there is a V class of defects of carious dental hard tissues of origin and later by other authors of this classification has been added to grade VI.

I class – cavity localized in the natural fissures and grooves of incisors, canines, molars and premolars.

II class – cavity located on the contact surfaces of molars and premolars.

III class – cavity located on the contact surfaces of incisors and canines without violating the cutting edge.

IV class – cavity located on the contact surfaces of incisors and canines in violation of the angle of the tooth crown and its cutting edge.

V class – cavity located in the cervical area of ​​all groups of teeth.

VI class – cavity located on the tops of hills molars and premolars, as well as on the cutting edges of the incisors and canines.

When dissection of hard tissue of teeth on the non-carious lesions are also guided by the classification and preparation HEREUNDER Black. For example, a wedge-shaped defect and enamel erosion, localized in the cervical area, belong to the V class.

FEATURES OF FORMING II CLASS CARIOUS CAVITIES.

 Variants of localization of carious cavities on the contact surfaces of molars  and premolars.

At presence of neighbouring tooth and maintainance of intact masticatory surface of diagnostician and instrumental access to the carious cavity of the II class in a number of cases present certain difficulties. For clarification of diagnosis and depth of defeat of hard fabrics of tooth sometimes come running to sciagraphy and other additional methods of inspection (luminescent stomatoskopia).

Preparing and stopping of the carious cavities localized on the contact surfaces of premolars and molars have some features.

1.   Separation   of teeth.   At the close location of teeth separacia (disconnection) of teeth is the initial stage  of preparing of cavities. Separacia foresees removing the sharp overhanging edges of enamel by a desuraging disk.

Separacia not only facilitates access to the cavity subject to preparing, not and at stopping of her is instrumental in the best trying to the walls of stopping material, and also the best renewal by stopping  (by an inset)  of contact surface.

2. Leading out    of cavity    on    a  masticatory    surface.  In the case of localization of carious cavity close to the masticatory  surface  and  presence  of neighbouring  tooth. Make the leading out of cavity on a masticatory surface. Not only comfortable approach is thus created to the carious cavity but also terms get better for  fixing  of the future stopping. The hard  fabrics of masticatory surface, located above a cavity, thin  through  a karborundum’s   stone,  diamond  or   hard-alloy cone bur.

Preparing of carious cavity is made through an angular tip. The inaccessible for the direct review cavities located on the back surface of premolars and molars examine and process under the control a stomatological mirror.

3. Forming    of additional    supporting ground.   A volume and  character of this  stage concerne by the depth of carious cavity, magnitude of defeat of contact surface. The special difficulty is presented by forming of cervical wall. The formed cavity of the II class must be rectangular   with   the horizontally  located   step   in the cervical region of contact surface.

 Elements of carious cavity

In a carious cavity distinguish walls, corners, bottom, edges. Edges and walls limit the in gate of cavity. The walls of cavity are named depending on the surface of crown to which they fitting. Edges and walls the cavities turned to the threshold of mouth and adjoining to the cheek are named cheeks, turned to the tongue — tongues. The corners of cavity are named on walls generatrices them: cheek-middle and turned to the middle plane — front, turned back — back. Consider the formed surface turned to mash the bottom of cavity, or pulp wall, regardless of localization of carious cavity.

 In the formed cavity of the II class (similarly as – cavities III and the IV classes) distinguish the basic cavity formed as a result of carious, and additional, which is formed in an intact enamel and dentine with the purpose of creation of comfortable approach   or  the best  fixing   of the permanent  stopping.

At a middle and deep caries in order to avoid injuring of mash removing of the staggered dentine from the bottom of cavity is made taking into account the topography of crown cavity of tooth. With the special carefulness form a near gum wall. Thus save the layer of dentine above the nearest horns of mash due to creation of additional supporting step. At the maintainance of rectangular basic cavity the form of additional cavity in area of masticatory surface can be very various: cruciform, three-cornered, in a kind swallow’s tail and other.

A supporting additional ground is instrumental in the best fixing of stopping and protects stopping from displacement during mastication. At comfortable approach to the carious cavity of the II class and absence of neighbouring tooth or if making on the tooth of artificial crown is assumed it is possible to be limited to forming of cavity within the limits of contact surface, not violating the verges of crown and masticatory surface.

FEATURES of FORMING of CARIOUS CAVITIES of a III  CLASS

A form and sizes of cavities of the III class in a great deal concerne by availability to the carious cavity and degree of defeat of its walls. Shallow carious cavity at presence of wide between teeth interval or absence of neighbouring tooth can be formed within the limits of contact surface of tooth. The thus formed cavity more frequent has the appearance of triangle foundation of which is turned to the neck of tooth, and sides are parallel to the vertical verges of crown. The top of triangle is turned to the cutting edge.

For the best fixing of stopping a near gum wall is formed under a direct or acute angle in relation to a bottom (to the pulp wall). Preparing of cavity is made the fissural cone burs and back conical. On occasion at a shallow carious cavity for the best fixing of stopping on the tongue surface of crown it is necessary to form an additional cavity (ground). The bottom of carious cavity can be protuberant for the maintainance of sufficient layer of dentine covering mash. With the purpose of the best fixing of stopping in a number of cases create strong points in a subject dentine, in one of the most well saved walls of cavity.

The carious cavities of the III class can simultaneously, to be localized on both contact surfaces or on contact surfaces and in a near neck region. The combined form of cavity can serve as the method of choice in similar cases.

From considering of aesthetics the lip surface of crown of the tooth is maximally saved even in default of subject dentine. Thus especially carefully delete a pigmented dentine, to eliminate possibility of x-raying of him through an enamel.

At simultaneous destruction of tongue and lip walls it is necessary to aim to save the corner of crown, which is near-by the hearth of defeat.

If the vestibular (labial) surface of crown is engaged in a carious, but was well saved tongue, preparing   is carried   out from the side of   threshold   of mouth.

By the obstacle for forming of near gum wall of cavity III     (IV) class there can be the hypertrophy of between tooth papilla growing   in  this   cavity.   The in this case   inflamed   papilla coagulating or  excise.  The further  forming   of cavity is carried out after cicatrized by wounds.

FEATURES OF FORMING OF CARIOUS CAVITIES OF  IV CLASS

By a basic    task    at   forming    of carious    cavity IV       class there is  renewal  of the blasted  corner   of crown of the tooth. Preparing of carious cavity is composed from two stages: treatment   of basic   cavity   and   forming   of additional supporting ground which is instrumental in fixing of stopping and hinders to its displacement in lateral direction.

Sometimes for clarification of correlations of bottom of carious cavity of the IV class with a crown cavity the sciagram of tooth is needed. A basic carious cavity is processed the same as cavity of the III class. Preferably to conduct preparing of cavity from a tongue surface, maximally saving hard fabrics of lip surface. During working as the cone bur it is necessary to take into account the closeness of location of horn of mash and presence in relation to the skims of enamel and dentine in a near neck region.

Place for an additional supporting ground and form she is determined taking into account magnitude by the defeats of hard fabrics and state of cutting edge of tooth. At a small carious cavity and wide effaced cutting edge an additional ground can be created as a longitudinal ditch along a cutting edge. At more vast carious cavity it is necessary economy to excise fabrics of basic cavity (especially in area of corner of crown), and to form an additional ground next to a tongue roller. An additional supporting cavity is formed as an oval, triangle, swallow’s tail under some corner to the basic cavity. Both in a basic and in additional cavity in the most saved areas of hard fabrics through the wheel-shaped cone burs do shallow furrows, niches, deepenings cooperant to strengthening of the future stopping. At forming of bottom of cavity take into account both localization and curvature of crown cavity of tooth. At renewal of the blasted corner of cutting edge of crown in pulp tooth for the best fixing of stopping in the most saved walls of crown fasten metallic framework from klammer wire.

Treatment of posterior proximal lesions – II class cavities

Caries on the proximal surfaces of posterior teeth occurs because plaque can collect cervical to the contact area, resulting in a stagnation area (or plaque trap). The diagnosis of proximal caries requires careful clinical examination of the marginal ridges; this area may appear darker or more opaque than surrounding tooth tissue.

Bitewing radiographs are essential for the diagnosis and assessment of posterior proximal lesions. If the lesion is confined to enamel, as assessed radiographically, then it may be possible to arrest, or even reverse, the progress of the caries. Appropriate dietary advice and interdental cleaning instruction should be given and fluoride, either as an operator-applied varnish or in toothpaste, should be used.

If the lesion has cavitated and spread into dentine then operative intervention will normally be necessary to restore the surface integrity of the tooth. Access to caries on the posterior proximal surfaces may be gained in a number of ways:

■ Through the marginal ridge from the occlusal aspect. The most common technique to gain access to the caries is through the marginal ridge from the occlusal surface of the tooth and this technique will be described in detail.

■ From the occlusal surface (tunnel preparation), preserving the marginal ridge. The tunnel preparation is difficult to execute unless there is a pre-existing occlusal restoration which is removed and access to the proximal caries can be gained from the occlusal cavity, without removing the marginal ridge. This technique is not suitable if there is extensive proximal caries as the marginal ridge will collapse. The main difference between this method is that during preparation contact point is preserved, access to the carious cavity is created from the occlusal surface like a tunnel. This method helps to preserve the most of unmodified tissue. This preparation is recommended to be carried out with turbinehandpieces, round-shaped burs with the simultaneous cooling of water.

■ From the buccal (or lingual) aspect. This technique is only suitable where there is no risk of marginal ridge collapse and in situations where resin composite can be used as the restorative material.

■ Directly, if the adjacent tooth is absent.

 Technique for posterior proximal restorations through the marginal ridge

■ Local analgesia is usually required.

■ Check occlusion and mark occlusal stops with articulating paper.

■ Ensure effective isolation.

■ Protect adjacent teeth: some operators like to place a matrix band on the adjacent tooth to prevent damage of this tooth during preparation of the box component of the cavity. This is no guarantee that the tooth will not be damaged and care should always be taken in the preparation of proximal cavities to protect the adjacent tooth.

■ Gaining access: access is gained through the marginal ridge using a pear-shaped diamond or tungsten  carbide bur in a high-speed handpiece. Start slightly away from the marginal ridge and direct the bur downwards and towards the contact area. The bur should drop down into the caries. Try to leave a thin wall of proximal enamel to protect the adjacent tooth. This can be removed subsequently with gingival margin trimmers. This creates a shape described as a box but it should not be square: it should have round internal line angles and should be wider cervically than occlusally. If there is also occlusal caries then the cavity should be extended into the occlusal fissure. If there is no occlusal caries then the cavity does not need to extend into the fissure.

 

■ Caries removal: caries should be removed with a round stainless steel or tungsten carbide bur in the slow-speed handpiece. Remove the caries from the enamel dentine junction first before moving to the axial wall (and pulpal floor if the cavity has been extended into the occlusal fissure). An excavator may also be used to remove soft dentine caries. This should result in a cavity that clears the contact area cervically and is wider cervically than occlusally.

■ Retentive features: additional retentive features are only necessary if amalgam is to be used as the restorative material. If the cavity has extended into the occlusal fissure then this will act as a key or dovetail to retain the amalgam and prevent its displacement. If there is no occlusal key and amalgam is to be used, then small grooves should be cut at the junctions between the axial wall and the buccal and lingual walls.

■ Lining: if the cavity is suitably deep to require lining then this should be placed on the pulpal floor and on the axial wall.

 ■ Matrix band: a matrix band is placed to help retain the restorative material during placement, to give shape to the proximal surface of the restoration and to allow close adaptation of the restorative material to the cavity. The band should be closely adapted to the cervical margin and should be burnished against the adjacent tooth to help formation of a good contact. There are many types of matrix bands and holders, but commonly used ones are:

? Siqveland: this system uses a straight band and the holder and band are removed from the tooth simultaneously. This can sometimes result in removal of part of the newly packed amalgam.

?  Tofflemire: this system has the advantage that the holder is removed before the band and this may  prevent removal of the restoration with the band.

?  Circumferential: a number of systems exist that have no retainer/holder. The band is tightened by  a spring mechanism.

?  Ivory: this has a holder which engages into a selection of holes in a metal band. The metal band replaces only one proximal wall and therefore  cannot be used for cavities involving both proximal walls.

■ Wedge: the next stage is to place a wedge at the cervical margin of the band, normally from the buccal aspect. The wedge has several functions:

?  It separates the teeth slightly so that when the matrix band is removed there is no space between the adjacent teeth and a tight contact is formed. Wooden wedges swell slightly by absorbing moisture in the mouth so are preferable to plastic wedges.

?  It prevents excess material at the cervical area of the cavity forming a ledge.

?  It shapes the band at the cervical margin of the tooth.

?  It can help retain the band in place.

■ Material placement (amalgam): once the amalgam has been mixed, it starts to set so the operator must work quickly to pack and carve the restoration. The amalgam is transferred in increments from the amalgam carrier to the deepest area of cavity – usually the base of the box. It is condensed first with the wider end of the amalgam condenser and then with the narrower end. It is important to condense the amalgam well to adapt the material to the cavity walls and to reduce porosity. Place the next increment, condense and  continueuntil the cavity is over-filled. The cavity is over-filled to allow removal of the weak, mercury-rich (γ2) layer that is at the surface of a well-condensed amalgam. Run a straight probe around the inside surface of the matrix band to remove gross excess of amalgam and to start to shape the marginal ridge. Carefully remove the wedge, matrix retainer and band. Check the cervical margin for excess amalgam with a straight probe and remove any excess, either with the probe or an amalgam carving instrument, such as a ? Hollenbach. Use an instrument designed for carving as it will cut through the amalgam, rather than smearing it (as would be the result if a flat plastic were used).

Using the tooth as a guide, rest the blade of the carver against the tooth and carve through the amalgam to recreate the cuspal shapes of the tooth. Check that the marginal ridge is a similar height to that of the adjacent tooth. Check the occlusion by asking the patient to close gently on the restoration. Listen for the sound of the teeth coming together and any impact on the amalgam. Look for any high spots and adjust. Should the amalgam fracture at this stage, it is better to remove the partially set material and start again, rather than try to add to the fractured amalgam.

■ Material placement (resin composite): dental adhesive should be applied to all the surfaces and margins of the cavity. The first increment of restorative material may be placed either at the base of the box or to form the proximal wall. Light cure for the recommended time, then place the next increment, ensuring that this increment only touches either thebuccal or lingual wall but not both (Fig. 13.7). Light cure and continue with incremental packing and curing. Carefully shape the marginal ridge by running a straight probe round the inside of the matrix band and finally recreate the cusp shapes to give the correct occlusal contour. Remove the wedge, matrix holder and band and check cervically for excess material. Check the occlusion by asking the patient and by the use of articulating paper. Shape and polish as required.

 

Treatment of anterior proximal lesions – III class cavities

Caries occurs on the anterior proximal surfaces owing to the accumulation of plaque gingival to the contact area. Detection of these lesions is by direct vision or bytransillumination: reflected light in the mouth mirror.

The technique for treatment of these lesions is as  follows:

■ Gaining access: access to the lesion should be from the palatal or lingual aspect if at all possible, as this will allow preservation of the labial enamel. A small round diamond in the high-speed handpiece is used to drop into the caries.

■ Removal of caries: a round bur in the slow-speed handpiece is used to remove the caries, trying to  preserve the labial enamel. Additional preparation to create a retentive cavity will probably not be necessary as the shape of the carious lesion will result in an undercut cavity. With adhesive restorations, an undercut cavity is unnecessary and amalgam restorations are contraindicated in anterior proximal cavities primarily because of their poor appearance.

■ Lining: a lining should be placed as required. Beware that calcium hydroxide lining materials are opaque and can look unsightly through thin labial enamel.

■ Matrix: a clear cellulose matrix strip should be placed before use of the dental adhesive to prevent bonding the adjacent teeth together. The strip should be placed so that it is cervical to the gingival margin of the cavity.

■ Dental adhesive: apply the adhesive to the cavity and the cavity margins.

■ Material placement: place the resin composite in the cavity in small increments and light cure. After the final increment has been placed, pull the matrix band tight cervically to prevent formation of a ledge, and light cure.

■ Finishing: check the occlusion as before and finish as required.

Treatment of incisal edge lesions – IV class cavities

Incisal edge lesions are the result of trauma, failure of a proximal restoration or extensive proximal caries.

The technique for treatment of incisal edge lesions is as follows:

■ Access: access to the lesion is not normally difficult;  the difficulty is creating good bonding potential. A labial bevel or chamfer will increase the area of tooth tissue for bonding and will improve the appearance of the final restoration as it will allow the composite to merge gradually with the tooth, rather than having a butt joint. Palatally, a small shoulder will increase the strength of the restoration in this area of occlusal loading. The lack of cavity walls has the advantage of reduced stress from polymerisation shrinkage.

■ Lining: in trauma cases, direct or indirect pulp capping with setting calcium hydroxide may be necessary.

■ Composite placement: composite can be built up free-hand or by using a matrix. To achieve optimal appearance, composites of different opacity, such as ‘dentine’, ‘body’, ‘enamel’ and translucent, should be built up in incremental layers. The types of available matrices are:

?  Custom-made: an impression of the palatal aspect of an intact tooth can be used to aid formation of this aspect of the final restoration. To achieve an intact tooth, a temporary restoration can be placed, or a laboratory wax-up used.

?  Preformed: the main types used are clear cellulose strips, incisal corners and complete crown forms.

■ Shaping and finishing: the adjacent teeth may be used as a guide to the shape of the final restoration. Care should be takeot to damage the remaining tooth  tissue in the polishing of incisal edge restorations when it may be difficult to distinguish between tooth and restoration.

 Definition of cavity:

Is defined as a defect in enamel, dentin or cementum resulting from the pathological processes, mostly the dental caries. Other processes such as abrasion, erosion etc. can also cause such defects.

Cavity preparation:

It is defined as the mechanical and surgical alteration of a defective, injured or diseased tooth in order to best receive a restorative material which will re establish a healthy state for the tooth including aesthetic corrections where indicated along with the normal form and function.

Cavity preparation is the performance of those dental surgical procedures required to expose the carious lesion, permit of removal of affected tissue and so shape the remaining dentin and enamel as to receive a restoration to its original form and function give it strength and prevent re occurrence of decay in the same surface.

History:

Cavity preparation techniques have been known for many centuries. During the ninth century itself cavities have been prepared for dental inlays.

During the early 19th century, cutting was done mainly by hand-operated instruments. Later drills operated by bowstring, Archemedian drives were used. Dr. Samuel Fastlich has suggested that the Mayas used tube drills and bow drills.

During the late 19th century pedal driven engine using flexible cables, hand piece and burs came into existence. Page-Chayas hand piece, the first belt driven angle hand piece to operate successfully at speeds over 100,000rpm was introduced in 1955. In 1957 the first clinically acceptable air turbine hand piece Borden airotor handpiece came into play. Then Air motor, Electric micro motor, straight handpiece, right angled handpiece and contra-angled handpiece were introduced. At the latest, now air abrasion and lasers are being used.

Hamelton Jameson for the first time in the 19th century emphasized the need for organized cavity preparation. He suggested the following steps:

• Removal of soft and infected dentin using hand instruments.
• Sterilization of dentinal surface.
• Retention form using dentinal buttons.

In 1930’s G.V. Black, gave the systemic approach to cavity preparation with special emphasis on retention form. Black’s principles of cavity preparation were specially meant for metallic restorations. Several operators, with the intention of improving aesthetics, had modified some of the original suggestions of Black.
Dr. Charles E. Woodbury suggested that the labial margin of the preparation to be in harmony with the lines of refraction of the labial surface. Henry A. True suggested another inconspicuous type of preparation using a special “slant technique”.
Introduction of new aesthetic restorative materials, particularly during the last two decades have changed the conventional ideas of cavity preparation, probably this is the only area wherein Black’s general principles are becoming obsolute. Conservative cavity designing is done by limiting the preparation of the cavity only to the areas affected.

Classification of cavities:

Based on the type of treatment and the areas involved, Black gave his classification.

CLASS I

All pit and fissure cavities.

IA Cavities on the occlusal surface of molars and premolars.
IB Cavities on the occlusal 2/3rd of the facial and lingual surface of molars.
IC Cavities on the lingual surface of maxillary incisors.

CLASS II

Cavities on the proximal surface of molars and premolars.

CLASS III

Cavities on the proximal surfaces of anterior teeth that do not involve the incisal edge.

CLASS IV

Cavities on the proximal surface of anterior teeth that involve the incisal angle.

CLASS V

Cavities on the gingival third of the facial and lingual surface of all the teeth.

CLASS VI

Cavities on the incisal edge of anterior teeth or the occlusal cusps of posterior teeth.

Following are some of the objectives that one should keep in mind while preparing a cavity

1.To remove all defects and give the necessary protection to the pulp.
2.To locate the margins of the restoration as conservatively as possible.

3.To form the cavity so that under the force of mastication the tooth or restoration or both will not fracture and restoration will not be displaced.

4.To allow for the aesthetic and functional placement of a restorative material.

Resistance form may be defined as that shape and form of cavity walls that best enable both the restoration and the tooth to withstand occlusal forces without fracture.

Fundamental principles involved are:

1.Box shape or mortise shaped with flat floor, which helps the tooth to resist occlusal loading by virtue of being at right angles to the forces of mastication.

2.Slightly curved than acute line angles decrease the stress concentration of stresses and hence reduce the incidence of fracture.

3.Conservation of strong cusps and ridges with sufficient dentin support.
Weakened areas should be included in cavity preparation to prevent fractures (capping of the weakened cusps).

4.To provide enough thickness of restorative material to prevent fracture under load.

5.Slight roundening of the line angles to prevent stress concentration.

STRESS PATTERNS OF TEETH

According to Gabel application of mechanical principles to the design of restorations will help conceive favorable stress patterns for the teeth and the restorations. These principles vary according to the type of restoration and cavity.

TYPE OF RESTORATION:

The minimal thickness of amalgam and cast gold to resist fracture is approximately 1.5mm, though a little more depth is required for amalgam to achieve the requisite bulk. However in composite and glass ionomer, the depth is not the criteria for achieving resistance form. Porcelain also requires a depth of 2mm for inlays and 1.5mm for crowns.

TYPE OF CAVITY:

CLASS I:

A flat pulpal floor is appropriate. In case of deep caries where a rounded pulpal floor may result, the stress is doubled in the deepest portion of the cavity. Fractures in these rezsstorations are due to insufficient dentinal thickness in the center. Bending stresses are proportional to square of depth. Therefore for large restorations depth should be increased with increase in diameter.

CLASS II:

A proximo-occlusal inlay restoration acts like a curved beam of cantilever type. Due to differences in modulus of elasticity of dentin and the material there will be displacement of the restoration in the gingival seat area with the axio-pulpal line angle as axis of restoration. This is prevented by a lock in the form of groove pins, etc in the gingival floor. In M.O.D. cavity axio-pulpal line angle should be more rounded.

CLASS III:

Due to the thickness of incisal edge the cavity is extended lingually as close to the incisal edge as possible.

CLASS V:

The functional cusp and functional fossa relationship dictates the stress pattern.

EFFECT OF GROOVES:

Grooves provide resistance to a certain degree. Courdadee and Jimmerman have shown that localized areas of stress are produced in tooth tissue by provision of supplemental intracoronal retention in the form of pins.

RETENTION FORM

Retention form is that form of cavity that best permits the restoration to resist displacement through tipping or lifting forces, especially masticatory loading.

PRINCIPAL MEANS OF GAINING RETENTION

• Inverted truncated cones or undercuts.

• Dovetail.

• Elastic deformation of dentin e.g. gold foil.

• Friction – which depends on surface area, opposing walls or surfaces involved, parallelism or non-parallelism, proximity of material to walls.

OTHER MEANS:

• Grooves

Mainly indicated in cast restorations, they are prepared in the walls of the proximal box inside the DEJ. The depth is equal to the width. They are placed at the axiobuccal and axiolingual line angles, putting more pressure on the buccal and lingual walls rather than on the axial wall. They are prepared parallel or slightly diverging occlusally for the proper withdrawal of the pattern.

• Internal boxes

• Posts

• Pins

Provide extra retention and can be used with amalgam, composite and cast restorations.

• Triangular areas (gold foil)

• Etching:

Provides micromechanical retention by increasing the surface area for retention. This is mainly indicated in bonded restorations.

• Slots:

They are prepared in dentin to increase the surface area of the preparation and have more convergent walls. These are 1 – 1.5mm deep box type preparations and can be given 9in occlusal wall or gingival wall or both. Usually they are given all along the width of the occlusal / gingival wall. Each of it has four walls that aids in retention.

• Locks:

They are given in proximal box of class II cavity and are indicated mainly for amalgam restorations. They are given in dentin either in the walls of the proximal box or in the occlusal box at the line angles which the pulpal wall of the cavity makes with the occlusal wall. These are 0.2 to 0.3 mm wide and 0.5mm deep into dentin.

• Skirts:

Mainly indicated in cast restorations, they are extensions of the proximal box at the line angles of the tooth or even away from it. The margins of the restorations are kept on healthy tooth structure and bevelled. The enveloping of the walls increases the surface area and aids in retention.

AMALGAM:

Retention is enhanced by

• Parallel walls and flat pulpal floor or gingival floors

• Occlusal convergence of walls (axial retention) in class of class II.

• Occlusal convergence and dovetail

• Proximal retention in the from of axiofacial and axiolingual locks

• Slots in gingival floor.

CAST GOLD RESTORATIONS

Axial retention in the form of cement locking and friction in micro-irregularities.

This is enhanced by

• Parallelism.

A slight divergence of the walls 2 degrees-5 degrees can be given for proper withdrawal of the pattern. In case the available height of the walls is less, the divergence should be kept minimum. At least one half of the walls should be kept parallel and the rest can be diverged.

• Increase in area.

Occlusal extension is mandatory since it prevents tilting of the restoration.

• Increase in strength of cementing media.

• Sharp line angles except axiopulpal line angle.

• Lateral retention by dovetail and pinholes and pot holes.

TOOTH COLORED RESTORATIONS

Retention is achieved by

• Acid conditioning.

• Retentive cavity preparation.

• Physico-chemical retention.

• Posts.

DIRECT GOLD

Retention is established by

• Elastic compression developed in dentin because of condensation.

• In classIII-undercut at point angles.

• In class IV-grooves along occlusopulpal and gingivopulpal line angles.

CONVENIENCE FORM

Convenience form is defined as that form of cavity preparation that allows adequate observation, accessibility and case of operation in preparing and restoring the cavity.

Modification in tooth preparation for convenience form:

Occlusal step in classII.

Labial/lingual access for classIII/classIV.

Occlusal divergence of cavity walls in cast restorations.

INSTRUMENT MODIFICATION:

Contra angling

Bayoneting
Addition of angles to the shank of the instrument.

SEPARATION:

Wedging of teeth.

SUPPORT OF ENAMEL RODS:

ALL enamel walls should be supported by sound dentin.

CAVOSURFACE ANGLES FOR DIFFERENT RESTORATIVE MATERIALS

Amalgam-90 degree cavosurface

Inlay- beveled cavosurface (20-40 degrees)

The margins should always should be always located on self-cleansing areas. They should be in smooth curves.

INSTRUMENTATION

Low speed with tungsten carbide burs are preferred for finishing cavity walls and the margins, as there is lessening of tactile sense and rapid removal of tooth structure with high speed.

REMOVAL OF REMAINING CARIOUS DENTIN OR OLD RESTORATIONS:

It is the elimination of any infected carious tooth structure or faulty restorations left in the tooth after initial cavity preparation.

Caries left in the pulpal/ axial floor is excavated thoroughly making the cavity deeper. 0.75- 1 mm of dentin should cover the pulp. All the infected/ soft dentin should be removed.

Old restorative material should be removed if:

1. The material may negatively affect the esthetic result of the new material.
2. It weakens the needed retention.

3. Secondary caries is present.

4. Tooth pulp is symptomatic.

5. Periphery of the old restorative material is not intact.

PULP PROTECTION

Though not taken in principles of cavity preparation it is one of the important steps before final restoration.

Pulpal injury can result due to:

1.    Heat generated by injudicious cutting.

2.     Restorative material with good thermal conductivity.

3.     Chemical from the restorative materials.

4.     Galvanic currents

5.     Microleakage.

Liners and bases are used fro pulp protection. Liners are volatile or aqueous suspensions or dispersion of zinc oxide or calcium hydroxide that can be applied to the cavity surface in a relatively thin film.

Bases are those cements, which are applied, in thicker dimensions beneath permanent restorations to provide for mechanical, chemical and thermal protection of the pulp.

FINISHING OF THE CAVITY WALLS

It is the further development, when indicated, of a specific cavosurface design and degree of smoothness that produces the maximum effectiveness of the restorative material being used.

OBJECTIVES:

1.    To create the best marginal seal possible between the restorative material and the tooth structure.

2.     Afford a smooth marginal junction.

3.     Provide maximum strength of both tooth and the restorative material at and near the margin.

Factors to be considered:

1.    Direction of enamel rods.

2.     Support of enamel rods at DEJ and cavity margins.

3.     Type of restorative material to be used.

4.     Location of the margin.

5.     Degree of smoothness desired.

The strongest enamel margin is that margin which is composed of full length of enamel rods that are supported on the cavity side by short enamel rods, all of which extend to sound dentin.

Line angles formed by the junction of enamel rods should be rounded whether acute or obtuse.

FEATURES:

There are two primary features related to the finishing of enamel walls:

1. The design of cavosurface angle:

For amalgam the cavosurface angle should be 90 degrees due to low edge strength of amalgam. However when extending the facial and lingual walls in treating extensive occlusal caries, tilting the bur is often indicated to conservatively extend the margin and provide a 90 – 100 degrees cavosurface angle. For cast gold/ metal/ composite restorations bevelling of external walls is done. Margins of gold foil restorations form a cavosurface angle much less obtuse than for gold / metal castings and composites. The bevel of the cavity margin in preparation for castings should produce a cavosurface angle of 30 – 40 degrees marginal metal. Providing a 30 degrees bevelled metal will provide with a sliding lapp type fit that definitely improves adaptation of metal to tooth at this margin.

2. The degree of smoothness of wall:

The advent of high-speed cutting procedures ahs produced two pertinent factors related to finishing enamel walls lessening of tactile sense rapid removal of tooth structure.

Plain cut fissure burs produce the finest surface. The prepared wall of inlay/ onlay requires a very smooth surface to permit undistorted impressions and close adaptation of the casting to enamel margins. In amalgam, goldfoil, composite, a very smooth surface is not desired as it decreases the retention.

TOILET OF THE CAVITY

This is the act of freeing the preparation walls and margins from objects that may interfere with proper adaptability and behavior of the restorative material.

It is accomplished by

• Removal of all enamel and dentin chips due to excavation and grinding with warm water.

• Drying with air syringe.

• Sterilization.

Englander et al have shown that silver nitrate and alcohol cause irreparable pulp damage if these are allowed to enter into the dentinal tubules.
Shay, Allen et al have shown that ZnOE, Ca(OH)2and fluoride content in some restorative material s show certain amount of protection even on unsterilized condition of cavities.

SMEAR LAYER

Later based on research debridement comprised of cleaning the cavity with warm water so as to protect the smear layer formed. Smear layer prevents penetration of bacteria and their products further into the pulp dentin complex through the dentinal tubules. Further treatment with caustic solution damages smear layer.

Changing concepts in Class I and II cavity preparation

From the time G V Black, father of Operative Dentistry outlined the principles of cavity preparation, and stressed on “extension for prevention”, dentistry has taken long strides. It is high time we fully realised the importance of preserving healthy tooth structure. Cutting sound tooth tissue is akin to murder of a person. Here, we are hastening the downslide journey of the tooth to its pulpal death.

Factors necessitating change of approach to tooth preparation are availability of

• improved amalgams.

• instruments with very small working points.

• amalgam bonding systems.

• adhesive restorative materials.

Clinical approach

For incipient carious lesions, preventive resin restorations(PRR) should be employed. PRR is a conservative treatment that involves limited excavation to remove carious tissue, restoration of the excavated area with a composite resin, and application of sealant over the surface of the restoration and the remaining sound, contiguous pits and fissures. PRR completely eliminates the age old “extension for prevention”, which is now considered as “extension for destruction”.

If you are proceeding with amalgam restorations for a Class I incipient lesion, use a pear shaped bur to remove only the carious area. The cavity depth need be only 1 to 1.5 mm for a high copper amalgam restoration. Make sure you have amalgam pluggers with very small working points so that you don’t have to widen the cavity to provide convenience form. As an emergency measure, you can even cut off and flatten the tip of a straight probe to be used as amalgam condenser.

For Class II amalgam cavities, Markeley recommended a much conservative approach with a smaller box and a considerably diminished isthmus. For a very small proximal lesion, a keyway or lock across the occlusal surface is not needed. Just place retention grooves on the buccal and lingual proximal walls with a thin tapered bur.

When proximal lesions are to be restored with adhesive restorative materials, there is no need to create conventional box preparation. Instead, there are two approaches.

1.     The external “trough”, “slot”, or “groove” preparation. This approaches the lesion directly, either from buccal, or lingual, or from the marginal ridge.

2.     The second type is the “tunnel preparation”, which is also known as “internal oblique preparation” “internal fossa preparation”, “internal occlusal diagonal or internal preparation”.

Tunnel preparation and restoration with a glass ionomer cement is possible due to the chemical adhesion of the cement, which will strengthen the weakened proximal enamel wall and marginal ridge The transference of fluoride ions offers caries protection to the adjacent tooth surfaces. Since the material allows the flow of moisture, the dehydration of the cusps is reduced, making them less vulnerable to future fracture. If there is any likelihood of occlusal load more than glass ionomer can withstand, then reduce the cement to DE junction and laminate with composite resin.

The Microchip proximal cavity preparation is a variation of the tunnel preparation when removal of the porous enamel into the marginal ridge area is required.

The mini-box proximal cavity preparation differs from the previous preparation in the handling of the enamel. Here, the integrity of the enamel wall needs to be ensured by extending the margin back to where it can be considered stable and durable.

For the gingival wall preparation, the remnants of the porous enamel is removed, and the enamel wall is taken down until stable structure is reached. This may leave the enamel wall occlusal to the dentin wall but the deficiency in the dentin can be easily restored with a glass ionomer cement.

ROTARY INSTRUMENTS

Slow speed

The slow-speed handpiece is driven either by compressed air or directly by an electric motor. The speed of the handpiece ranges from 0 to 40 000 rpm. The most efficient cutting is achieved with a straight handpiece, but this is difficult to use in the mouth and is therefore restricted to extraoral use, such as adjusting temporary crowns and dentures. The contra-angle handpiece is used for the removal of caries, polishing and finishing.

High speed

The high-speed handpiece is driven by compressed air and is sometimes referred to as an air-turbine or air-rotor.

It is used for cutting through enamel and dentine and removing previous restorations. It has a speed of 250 000–500 000 rpm and, to keep it cool, a water spray is directed at the cutting part of the bur which is held in the head of the handpiece by friction. A fibreoptic light in the head of the handpiece aids visibility.

BURS

 

BURS ARE DESCRIBED BY:

 

Cavity Preparation for Amalgam Restoration Class 2

Definition:

It is smooth surface lesion occurring on the proximal surface of molars and premolars just gingival to contact area.

1st: Outline form 

 External outline:

 1-The classical class 2 cavity has two portions:

 (1) The occlusal cavity.

 (2) The proximal cavity: which meet together at an area called isthmus portion (weakest part it’s  above the axial wall).

 2- The occlusal cavity similar to class 1 except that it has reverse curve for:

 (1) Be away from contact area. 

 (2) Cavosurface angle=90

 3- Proximal cavity location: at contact area to make it free and its gingival wall apical to contact area  by 1-0.5 mm. It’s CSA=90.

 Internal outline:

 1- occlusal cavity : similar to class 

 2- proximal cavity:

 (1) Buccal and lingual walls parallel to corresponding surface and converge occlusally and flaring  proximally.

 (2) Gingival wall apical to contact area by 1-0.5 mm.

 (3) Axial wall should be converge occlusally and convex bucco-lingually.

 (4) Axio-pulpal line angle should be rounded.

 (5) Gingival wall should be beveled apically.

 (6) Pulpal floor should be parallel to occlusal plane except in the 1st premolar.

2nd:  Resistance form: 

1- Restoration should be slightly diverge occiusally mesio-distally to give bulk to amalgam.

2- Undermined enamel and short enamel rods must be removed.

3- Flat pulpal and gingival floor parallel to occlusal plane and parallel to each other and perpendicular to tooth long axis.

4- Width of gingival floor (deep of axial wall) is limited to 1mm in premolars and 1.5 nun of molars under DEJ 0.5 mm in premolars and 1 mm of molars.

5- All walls are smooth and flat.

6- Line angels slightly rounded.

7- Axial wall inclines occlusally and convex bucco-lingually. (so we stay away from pulp horn). 

8- Rounded or beveled axio-pulpal line angel (to prevent stress concentration of forces at isthmus portion in order to prevent fracture of restoration).

9- CSA occlusally and proximally 90 dgree.

10- Axial wall is straight or inclined occlusally gingivo-occlusally.

11- The proximal preparation should have a mesiodistal dimension of about 1.5 mm or more.

12- If there is sound dentin supporting occlusal enamel in the fossa adjacent to the marginal ridge, that dentin and enamel should be left intact.

3rd:  Retention form:

 (1): occlusal portion:

 1- Buccal and lingual walls converge occiusally (prevent occlusal displacement).

 2- Dove tail lock (prevent proximal displacement).

 3- Undercuts (prevent occlusal displacement without undermining enamel).

 (2): B- proximal portion: By cutting 2 retention proximal axial grooves.

Undercuts:

1. If the extension into the occlusal surface is narrower, or if there is no extension into the occlusal grooves, as with the proximal slot restoration, retentive undercuts (retention grooves or points) must be cut into the dentin of the facial and lingual walls of the proximal box

2. For a proximal slot restoration, retentive undercuts should be very distinct (at least 0.5 mm deep) and should oppose each other to form a dovetail effect in the dentin. 

3. Long grooves, extending from the gingival floor to the occlusal surface, are recommended for a proximal slot restoration.

4. If the occlusal extension is narrow, short retention grooves, or retentive points, should be prepared in the dentin of the facial and lingual walls to supple-ment the resistance form provided by the occlusal extension.

5.  If there is a bulky extension of amalgam into the occlusal surface of the tooth, retentive undercuts should not be necessary.

6. Retentive undercuts in the dentin of the facial and lingual walls should be completely in dentin and not at the DEJ.

7. A good rule is to place retentive undercuts so that there is approximately 0.25 to 0.5 mm of dentin between the groove and the DEJ and so that the groove is approximately 0.5 mm deep and 0.5 mm wide.

4th: planning of enamel walls (Noy’s principles):

A- Enamel walls finished from any short or undermined enamel. 

B- Enamel walls meet tooth surface at right cavosurface angel. 

C- All sharp corners in enamel must be rounded. 

 Cavity Preparations for Posterior Composite Resins

Until recent times the recommended cavity preparations for the restoration of posterior teeth has remained unchallenged. As long as amalgam was “king”, there really was no need to change the “status quo”. It is interesting to note that the standard amalgam preparation basically was designed by one individual; Dr. GV Black. While it is true that the addition of retentive grooves and the convergence of the preparation towards the occlusal margins were contribution of others, the basic preparation design was authored by one person.

Black’s configuration was based upon several principles. Perhaps the most interesting related to his understanding of the plaque distribution and zone of greatest concentration of microbial agents.. Acknowledging that the distribution of microbes and plaque resembled a normal distribution curve in the proximal aspects of posterior teeth he designed the proximal aspect of the preparation accordingly. In essence the bucal-lingual dimension of his preparation was extended in such a way that in the general patient, the margins would lie outside of the normal distribution curve (bell-shaped). His reasoning was further enhanced by his apparent knowledge of the relationship between the wall of the preparation and the amalgam restoration. Regardless of the circumstance, an interfacial gap between the prepared wall and the amalgam averages 10 to 12 microns. Under such a condition, there is ample potential for caries producing microbes to enter into this interface. Reducing the distance between the extended walls of the proximal portion of the cavity preparation would automatically increase the potential for positioning these margins in an elevated plaque zone.

In the case of composite resin, there is no incidence of a marginal gap; at lest if the bonding procedure were carried out appropriately. Through acid etching and hybridizing of the dentin, the clinician eliminates the potential for microbial invasion. The location of these proximal margins then is far less important than it is with the corresponding amalgam restoration. For this reason the proximal walls of the preparation are not necessarily extended into a so called “self-cleansing” zone. It is then possible to minimize the dimension of the preparation which in turn increases the potential of an increased longevity.

Another consideration related to the composite resin preparation is the restoration of the central fissure and associated pits. Under normal circumstances, a mesial and/or a distal pit on a premolar are treated individually. In the days of Dr. Black, restoration of one or more pits with an amalgam would also mandate the restoration of the entire central fissure. The differences in procedure between yesteryear and today relate to the incidence of caries. One hundred years ago, the restoration of only the central pits would be followed up by secondary caries in the central fissure in a relatively short period of time. Identified as “extension for prevention” this form of treatment was certainly justifiable. Currently, with the far lower incidence of primary and secondary caries, the clinician can afford to be appreciably more conservative in cavity design. And again; the more conservative the preparation, the greater the longevity. 

As a general rule, the preparation for posterior composite resins is smaller in all three dimensions as compared to that for amalgams. Assume for the moment that a small lesion has occurred on the mesial aspect of the lower right first molar. The extension of the proximal aspect of the preparation should be no more than three millimeters in the bucal-lingual direction. No attempt necessarily needs to be made in breaking contact with the adjacent proximal surface. Next, the proximal portion of the cavity preparation should be extended into the occlusal surface by no more than two millimeters. If caries is present on both proximal surfaces, the clinician should not attempt to include the central fissure unless there is caries in the central fissure. A small pit lesion if present should be treated as a separate entity using a conservative bur such as a No. 243.  Finally, if conditions allow, the distance between the gingival margin and the cervical line should be at least two millimeters.

There is still one more interesting difference between preparations generated for composites as compared to amalgam. If, for instance, the clinician identifies a small pit lesion in the central fissure of a maxillary premolar, how deep does the preparatioeed to be extended if the defect falls short of the dentino-enamel junction?  If the restoration is to be a composite resin, the extension of the defect need not be extended any further. If on the other hand, the clinician is to place an amalgam the preparation needs to be extended beyond the dentin-enamel junction and into the dentin. In the case of amalgam, the masticatory energy is transmitted through the restoration and into the underlying surface. If the bottom of the preparation consists of enamel, the energy vector is reversed in the opposite direction which then results in an absorption of energy by the amalgam. After a sufficient number of cycles the amalgam undergoes microcracking and eventual failure. If the base of the preparation consists of dentin, the masticatory energy is partially absorbed by the dentin, thereby minimizing the trauma to the restoration thereby extending the longevity of the amalgam. Since the amalgam is bonded to the tooth, the tooth as well as the composite resin absorbs the energy. This principle is far different in the case of the amalgam.

One final point should be made. If an isthmus is to be established, it is important to minimize its width as much as possible. The bucal-lingual dimension of the isthmus determines the rate of wear of the composite resin on the occlusal surface. In the presence of a bolus of food and the energy of mastication, the composite gradually undergoes attrition. Minimizing the width of the preparation reduces the potential for contact by the food bolus. It also reduces the potential for contact by the antagonist cusp. Again, the smaller the dimension of the preparation, the greater the potential for longevity.

Cavity Preparation for Caries Restoration

Caries are the decay of the tooth structure. They can be restored using different dentistry methods. In this article, there is a brief discussion on cavity preparation for caries restoration. Let us examine them.

Modifications of cavity preparation in primary teeth

All the principles of cavity preparation of permanent teeth also hold good for the primary teeth. However, a few factors have to be taken into consideration while restoring the primary teeth. These include the following:

o  The smaller tooth dimension of the deciduous dentition

o  The thin enamel covering the teeth

o   Broad contact areas

o   Proximity of the pulp chamber to outer tooth surface

o   Narrow occlusal table

Class I cavities

o   Due to the narrow occlusal table present the isthmus should not be more than 1/3rd the intercuspal distance in the case of a small carious lesion.

o   he depth should not be more than 0.5 mm into the dentin.

o     The pulplal floor must be flat. Any remaining caries lesion should be removed using round bus.

o     Use of preventive resin restoration is advocated rather than the conventional cavity preparation which includes all pits and fissures.

Class II cavities

o     Due to the presence of broad contact areas, the gingival floor of the proximal box should be wide so as to place the margins in self cleaning areas.

o     The box should however converge occlusally with the buccal and lingual wall paralleling the external tooth surface.

o      The walls of the proximal box should meet the occlusal walls in a straight line to avoid any weak points.

o       The walls of proximal should not be flared as it would lead to unsupported enamel.

o       The isthmus should have just adequate width that is it should not exceed 1/3rd the intercuspal width in primary molars.

o       The axiopulpal line angle must be either rounded, tunneled or grooved for sufficient bulk of the restoration.

o       The strength of amalgam at the isthmus area can be increased by an adequate depth of the preparation.

o       Retention can be improved by a ‘U’ shaped retention groove along the amelodentinal junction of the proximal box.

o         When the cavity margins exceeded that of an ideal preparation particularly in the case of a mandibular first primary molar, it is recommended that an overlay of the distobuccal cusp be prepared. The weakened cusp is reduced to the level of the pulpal floor of the occlusal preparation. Mesiodistally the cusp should not be reduced more than 1/3rd the crown’s mesiodistal lenth.

o         Since the enamel rods, at the cervical area of the tooth are oriented occlusally the gingival seat must not be beveled, rather it should follow the enamel rod inclination.

o           If the depth of the lesion is farther gingivally, the axial wall should follow the contour of the external surface. This will prevent pulp exposure from occurring.

o         Care should be taken to avoid the mesiobuccal pulp horn in the case of small first molars. Since the contact with the canine is a point contact, the proximal box extension and the gingival flare can be minimized.

o         The proximal box should allow the passage of an explorer tip between its margin and adjacent tooth in all three directions, buccally, gingivally and lingually.

Class III cavity

o         When the contact is open, the outline is triangular with base towards the gingival aspect of the cavity.

o         Gingival cavity wall is inclined occlusally to parallel the enamel rod direction.

o       Retention pills can be placed at the axiobucco gingival and axio linguo gingival point angles.

o      A dovetail may be placed in the middle one third of the lingual surface of the tooth. This helps in gaining access to the carious lesion and in facilitating retention of the restoration.

Young permanent first molars

The following special morphological considerations should be kept in mind while preparing a cavity in a young permanent first molar.

o                    The first permanent molars erupt between the age of five and six years and this is the age group wherein caries is a common problem. These are often first of the permanent teeth to become carious.

o                    The result of various developmental interference will often result in failure of the enamel to unite completely and smoothly in the middle of the occlusal surface and there will be potential for faults and defects in the occlusal enamel, even before eruption.

o                    The occlusal surface of any tooth is particularly susceptible for plaque accumulation within a defect because of the heavy pressure to which this surface is subject to during mastication. Such fissures can be as far as 1.5 to 2mm deep into the enamel and it is possible for them to penetrate right through to dentin.

o                    They may range in width from 100 to 500 micrometers and will often be wide at the entry, narrow down to less than 200 micrometers and then open wider again at the dentin.

o                    In many cases, the fissures are made up of a series of pits of considerable depths rather than one continuous fissure.

o                    The result of this convoluted anatomy may be compaction of bacteria laden plaque into the depths of the fissure leading to active demineralization down the walls and into dentin with minimal visible evidence on the occlusal surface. In communities that have systemic fluoridation the enamel is often very hard and does not breakdown until it is severely undermined. This means that caries that has progressed through to the dentin can progress all the way to pulpal involvement without any visible breakdown on the occlusal surface.

o                    The enamel rods within a fissure are not always as regular in pattern as those elsewhere around the crown of a tooth. Those at the shoulder around the entry to a fissure are often gnarled and irregular and will not always accept a regular etch pattern. In the depths of a fissure there may be a layer of enamel rods lying parallel to the surface rather than at right angles.

o                    There is a likelihood of a carious lesion on the distal of the deciduous second molar extending some damage on to the mesial of the adjacent permanent tooth. The carious lesion may become visible and available for treatment at the time the deciduous tooth is exfoliated.

Kinetic cavity preparation

o                    KCP which used fined particles of powder fired at high speed in a controlled manner instead of the traditional high and low speed drills.

o                    Advantages of this technique are that no vibrations or pain sensation and also no need for anesthesia in most cases.

o                    This truly allows us to multiple quadrant dentistry so as to decrease the number of patient visits and better time utilization.

The above article discusses briefly about the cavity preparation for caries restoration.