4. Composite cavity preparation (1).pptx

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1. CAVITY PREPARATION FOR COMPOSITE RESTORATION Presented by, Guided by, Dr. Monisha Tiwari MDS I Year Dr. Rana .K. Varghese, Prof. and Head Dr. Gururaj . M, Reader Dr. Rishidev Yadav , Reader Dr. Minal Daga,Sr . Lecturer

2. CONTENTS Indications Contraindications Advantages Disadvantages Clinical techniques for direct class III composite restorations Clinical technique for direct class IV composite restorations Clinical techniques for direct class V composite restorations

3. Clinical techniques for direct class I composite restorations Clinical techniques for direct class II composite restorations Clinical techniques for direct class VI composite restorations

4. CLASS III , IV & V COMPOSITE RESTORATION

5. Indications: R estorations in esthetic prominent areas. A reas can be adequately isolated. T ooth preparations that have an all enamel margins.

6. Contraindications : A n operating area that cannot be adequately isolated. C lass v restorations that are not esthetically critical. R estorations that extends into the root surface (contraction gap ).

7. Advantages E sthetics C onservative of tooth structure removal L ess complex when preparing the tooth L ow thermal conductivity ( insulative ) Used almost universally

8. B onded to tooth structure

9. Disadvantages M ay result to gap formation R estoration is more difficult, time-consuming, costly M ore technique sensitive M ay exhibit more wear in areas of high occlusion H ave a higher linear coefficient of thermal expansion

10. CLINICAL TECHNIQUES FOR DIRECT CLASS III, CLASS IV AND CLASS V RESTORATIONS

11. Class III Tooth Preparation

12. Class III Tooth Preparation INITIAL CLINICAL PROCEDURE : 1.Anesthesia may be necessary for patient comfort . 2.Occlusal assessment should be made to help in properly adjusting the restorations function and in determining the tooth preparation design.

13. 3.The shades must be selected before the tooth dehydrates . 4.The area must be isolated to permit effective bonding. 5.If the restoration is large (including all of the proximal contact),inserting a wedge in the area before hand assists in the re-establishment of the proximal contact with composite .

14. TOOTH PREPARATION : 1 . Obtaining access to the defect(caries , fracture , non-carious defect ). 2 . Removing faulty structures (defective dentin and enamel , defective restoration etc ). 3 . Creating the convenience form for restoration .

15. Lingual Approach Indications : 1.To conserve facial enamel for enhanced esthetics . 2.Carious lesion is positioned lingually . 3.Lesion is accessible from the lingual .

16. Contra-indication : Irregular alignment of teeth. Facial positioning of the lesion .

17. Facial Approach Indications : 1.The carious lesion is positioned facially. 2.Teeth is irregularly aligned, making lingual access undesirable . 3.Extensive caries extent into the facial surface . 4.Faulty restoration that was originally placed at the facial.

18. Conventional Class III Indicated for restorations involving the root surfaces . 1.Using a No. ½, 1, 2 round bur prepare the outline form on the root surface. 2.Extend the preparation into sound walls. 3.Extend pulpally 0.75mm in depth.

19. 4.The gingival/cervical and incisal wall is perpendicular to the root surface (box like design ). 5.A continuous groove retention can be prepared 0.25 mm (½ of diameter of bur) into dentin of the gingival and incisal walls with a ¼ round bur . 6. The groove is placed at the junction of the axial and the external walls. 7. Clean preparation and inspect the final preparation.

20. Beveled Conventional Class III Indicated for replacing an existing defective restoration in the crown portion of the tooth . when restoring a large carious lesion for which the need for increased retention and/or resistance form is anticipated.

21. Lingual Access : 1.Use a round bur No. 1/2, 1. 2 depending on the size of the caries to enlarge the opening sufficiently to allow for caries removal . 2.Extend external walls to sound tooth structure using a straight bur.

22. 3.Extend the gingival and incisal walls up to extent of caries or location of old restoration. Unless necessary, DO NOT : include the proximal contact. extend into the facial surface. extend sub-gingivally .

23. Create an axial wall depth of 0.2mm into the dentin/DEJ (approximately 0.75 – 1.25mm in depth ).

24. 5.Axial wall is convex, following the external contour of the tooth . 6.Remove all remaining infected dentin, using a round bur or small spoon excavator . 7.Remove friable enamel margins .

25. 8.If necessary, prepare retention (grooves or coves ). prepare it along the gingivoaxial line angle, and sometimes at the incisoaxial line angle 0.25 mm with a ¼ round bur .

26. 9.Place cavosurface bevel or flare at the enamel except at the gingival margin area .

27. Use a flame shape or round bur resulting in a 45 degrees angle to the external tooth surface .

28. Bevel width should be 0.25 to 0.5mm . 12. Clean the preparation of any debris and inspect final preparation. Facial Access same stages and steps are followed . procedure is simplified because of easy access .

29. Modified Class III Most used type of cavity preparation. Indicated for small and moderate lesions or faults. Designed to be as conservative as possible. Preparation walls have no specific shapes or forms other than an external angle of 90 degrees or more degrees . Preparation design appears to be scooped or concave .

30. P reparation design appears to be scooped or concave, 1.Use a 1/2, 1, 2 round bur, point of entry is within the incisogingival dimension of the lesion, perpendicular to the enamel surface . 2.Remove all remaining caries or defect . 3.No attempt is made to create a uniform axial wall. 4.Place cavosurface bevel or flare at the enamel except at the gingival margin area.

31. 5. Use a flame shape or round bur resulting in a 45 degrees angle to the external tooth surface. Bevel width should be 0.25 to 0.5mm. 7. Clean the preparation of any debris and inspect final preparation.

32. Class IV Tooth Preparation

33. Class IV Tooth Preparation Pre-operative assessment of occlusion is very important (placement of margin in noncontact areas ). S hade selection is more difficult . P reparation is similar to Class III except that the preparation for class IV is extended to the incisal angles.

34. Class V Tooth Preparation Conventional T he feature of the preparation include a 90 degree cavosurface angle, uniform depth of the axial line angle, and sometimes, groove retention from . C onventional design is indicated only for portion of the lesion extended onto the root surface .

35. 1.Use a tapered fissure (No. 700, 701,or 271) or No.1 or 2 round bur . 2.Make entry at 45 degrees angle to tooth surface, this should result to a 90 degree cavosurface . 3.Axial depth is 0.75 mm ; -strength of preparation wall -strength of composite -placement of retention groove

36. Axial should follow contour of the tooth . Extent of outline form is dictated by the carious lesion extent . Remove remaining carious lesion. Prepare retention groove (similar to Class III preparation ). 8. Clean preparation .

37. Beveled Conventional Class V Indications : 1.Replacement of defective class V restorations. 2.Large carious lesion ; Exhibits 90 degrees of cavosurface. A xial wall depth is uniform (0.2mm or 0.5 when retention groove is to placed ).

38. G roove is not indicated when periphery of tooth preparation is located in enamel . R emove all infected dentin C lean preparation

39. Modified Class V I ndicated for small and moderate lesion and lesion entirely in the enamel. N o effort to prepare a butt-joint. N o retention groove. L esion is scooped out. P reparation has divergent wall.

40. Axial wall does not have uniform depth. Prepare tooth with round or elliptical instrument. preparation is extended no deeper than 0.2 mm. no effort is made to prepare a 90 degree cavosurface margins . infected enamel is removed with a round bur or excavator.

41. Class V Tooth Preparation for Abrasion / Erosion Abrasion – often V-shaped is a loss or wearing away due to mechanical forces. Erosion - often a saucer shaped notch as a result of chemical dissolutions

42. Abfraction/Idiopathic Erosion- may occur as a result of flexure of cervical area under heavy occlusal stress. This occurs as a notched defect . Modified tooth preparation is used for this types of defects.

43. Restorative Technique 1. Determines the shade of tooth.

44. Shade Selection: After caries removal and cavity preparation shade selection was done using shade guide .

45. Restorative Technique 1. Determine shade of tooth. 2 . Clean the tooth preparation using a slurry of pumice, polishing cup.

46. Restorative Technique 1. Determine shade of tooth 2. Clean the tooth preparation using a slurry of pumice, polishing cup. 3. Isolate the tooth, preferably with a rubber dam or cotton rolls.

47. Isolation of the Teeth: Rubber dam isolation technique was used to keep the prepared teeth from saliva, blood, debris and other fluids.

48. Restorative Technique 1. Determine shade of tooth 2. Clean the tooth preparation using a slurry of pumice, polishing cup. 3. Isolate the tooth, preferably with a rubber dam or cotton rolls. 4. Protect adjacent unprepared tooth from the acid etchant with a polyester strip apply the wedge.

49. 5. Apply the gel etchant 0.5 beyond the prepared margins onto the adjacent unprepared tooth. 6 . Etchant is left undisturbed for 15-30 seconds.

50. Etching Procedure

51. 5. Apply the gel etchant 0.5 beyond the prepared margins onto the adjacent unprepared tooth. 6 . Etchant is left undisturbed for 15-30 seconds. 7 . The area is washed to remove the etchant. Same amount of time as etching time.

52. 8. Dry the tooth structure, if dentin is exposed, do not air dry. Use cotton pellet, disposable brush or tissue paper to remove excess water.

53. 8. Dry the tooth structure, if dentin is exposed, do not air dry. Use cotton pellet, disposable brush or tissue paper to remove excess water. 9 . Bonding system is applied on all tooth structure that has been etched with a microbrush or other suitable applicators

54. 10. Air bonding system to thin out coating. 11 . Cure, follow manufacturer's direction.

55. Application of Bonding Agent: Application of the bonding agent and then cured for 10 seconds.

56. 10. Air bonding system to thin out coating. 11 . Cure, follow manufacturer's direction. 12 . Incrementally place composite material and cure.

57. Filling

58. Filling & Packing

59. Curing Of the Composite: The material is cured using the light curing machine for 20 seconds for every increment of composite that was placed.

60. Air bonding system to thin out coating . Cure , follow manufacturer's direction . Incrementally place composite material and cure . 13. Finish and Polish

61. Finishing and Polishing: The use of polishers with enhancers and polishing paste were done after the trimming of the excess composites.

62. Finishing & Polishing

63. Before the restoration procedure. After restoring with Composite Resin Material BEFORE AFTER

64. RESTORATIVE TECHNIQUE Placement of the adhesive : Step 1: The proximal surface of the adjacent should be protected from inadvertent etching by placing a Mylar strip or a Teflon tape. Step 2 : 37 % Phosphoric acid gel etchant is applied for 10 sec to all of the prepared tooth structure ,approximately 0.5mm beyond the prepared margins onto the adjacent unprepared tooth .

65. Step 3 : The area is rinsed thoroughly with the water spray to remove the etchant . Step 4 : It is clinically recommended to ‘blot-dry’ the etched area with the help of a damp cotton pellet , or a disposable brush to remove the excess water .

66. Step 5 : If the bonding system combines the primer and the adhesive, as in a one bottle etch and rinse adhesive ,the solution is applied next on all of the tooth structure that has been etched with the help of a microbrush . Step 6 : The adhesive is gently air dried with the help of the chip blower to evaporate any solvent (acetone , alcohol or water ) then light activated for 10-15 seconds ,as directed by the manufacture .

67. Insertion and Light Activation of the Composite : Composite material bonds directly to the polymerized adhesive . It is inserted by hand instrument or syringe . Light activated composites are usually available in two forms: A threaded syringe for manual dispensing and hand instrument insertion . A self contain compule that is placed into an injection syringe for dispensing or insertion .

68. Step 1 : If a threaded syringe is used the composite is picked up with the blade end of the hand instrument and wiped into the tooth preparation . It is also injected directly into the preparation by selected compule is placed into the injection syringe .

69. Step 2 : When the material has been inserted , it is light activated through the mylar matrix strip . A second increment of composite is applied ,if needed , to fill the preparation completely and provide a excess so that slight positive pressure can be applied with the matrix strip when closed .

70. Step 3 : With large restorations , it is better to light activate the composite in several 2mm increments to reduce the effects of polymerization shrinkage and to ensure complete light activation in remote regions . Step 4 : If two adjacent preparations are present ,that preparation with the least access is restored first .

71. CONTOURING AND POLISHING OF THE COMPOSITE Contouring and polishing instruments should be used according to the specific surface being contoured and polished . Special fine diamond finishing instruments,12-bladed carbide finishing disks can be used to obtain excellent results .

72. Step 1 : A flame shaped carbide finishing bur or diamond is recommended for removing excess composite on facial surfaces . Medium speed with light intermittent brush strokes and air coolant is used for contouring .

73. Step 2 : Excess lingual composite is removed using a round or oval –shaped 12-bladed carbide finishing bur or finishing diamond . A smoother surface is produced using a finer round or oval carbide finishing bur (with 18-24 blades or 30-40) or fine diamond at medium speed with air coolant and light intermittent pressure .

74. Step 3 : Abrasives disks mounted on a mandrel specific to the disk type ,in a contra-angle hand piece at low speed ,can be used instead of or after the finishing bur or diamond in facial surfaces and some interproximal and incisal embrassure .

75. Step 4 : A No.12 surgical blade mounted in a Bard-Parker handle is well suited for removing excess material from the gingival proximal area . This instrument is ideal for removing gingival overhangs .

76. Step 5 : Final polishing is achieved with rubber or silicone polishing instruments ,diamond impregnated polishers ,polishing disks,and polishing pastes . Step 6 : Further contouring and finishing of proximal surfaces can be completed with abrasives finishing strips .

77. Step 7 : Finally ,occlusion should be carefully checked in maximum intercuspation and eccentric movements by having the patient close on a piece of articulating paper and slide mandibular teeth over the restored area .

78. CLASS I ,II & VI COMPOSITE RESTORATIONS

79. Indications : For class I and class II : Small and moderate restorations , preferably with enamel margins . Most premolar and first molar restorations , particularly when esthetics is considered . A restoration that do not provides all of the occlusal contacts . A restoration that does not have heavy occlusal contacts .

80. A restoration that can be appropriately isolated during the procedure . Some restorations that may serve as foundations for crowns . Some large restorations that are used to strengthen remaining weakened tooth structure .

81. Contraindications : 1.When the operating site can not be appropriately isolated . 2.When heavy occlusal stresses are present . 3.When all the occlusal contacts are on composite only . 4.In restorations that extend onto the root surface .

82. Advantages : 1.Esthetics 2.Conservative tooth structure removal 3.Easier,less complex tooth preparation 4.Economics(compares with crown and indirect tooth -colored restorations ).

83. 5.Insulation 6.Bonding benefits Decreased microleakage Deacreased recurrent caries Decreased postoperative sensitivity Increased retention Increased strength of remaining tooth structure

84. DISADVANTAGES : 1.Material related Possible greater localised wear Polymerization shrinkage effects Linear co- eficient of thermal expansion Biocompatibility of some components unknown

85. 2.Require more time to place. 3.More technique sensitive Etching , priming , adhesive placement . Inserting composite Curing composite Developing proximal contacts Finishing and polishing 4.More expensive than tooth colored restoration .

86. PIT AND FISSURE SEALANT CONCEPT : Pits and fissure typically results from an incomplete coalescence of enamel and are particularly prone to caries . These areas can be sealed with a low viscosity fluid resin after acid etching .

87. Indications : 1.Sealants should be primarily used for the prevention of caries rather than for the t/t of existing caries lesion . 2.Only caries free pits and fissures or incipient lesions in enamel not extending to the DEJ currently are recommended for t/t with pit and fissure sealants .

88. Advantages : They provide an alternative to tooth preparation and restoration techniques for elimination of caries prone pits and fissures on occlusal surface . Materials employed : Most currently used material are : 1.Light-activated UDMA resin. 2.Light-activated BIS-GMA resin.

89. Clinical Technique : Step 1 : The tooth is isolated by using a rubber dam . Step 2 : The area is cleaned with a slurry of pumice on a bristle brush . Step 3 : The tooth surface is dried ,and etched with 37 % phosphoric acid gel for 15-30 seconds .

90. Step 4 : The sealant material is then applied with an applicator. Step 5 : The sealant is light activated for 15 seconds . Step 6 : The occlusion is evaluated by using articulating paper .

91. CLINICAL TECHNIQUE FOR CLASS I DIRECT COMPOSITE RESTORATION

92. TOOTH PREPARATION : 1.Creating access to the faulty structure . 2.Removal of faulty structures (caries , defective restoration and base material,if present ) 3.Creating convenience form for the restoration .

93. I. Small to moderate class I Direct Composite Restorations : Cavity design : These preparations are less specific in form ,having a scooped-out appearance without uniform or flat pulpal or axial walls .

94. Clinical Technique : Small to moderate class I direct composite restorations may use minimally invasive tooth preparations and do not require typical resistance and retention form features . They are prepared with a small round or elongated pear diamond or bur with round features .The initial pulpal depth is approximately 0.2 mm inside the DEJ .

95. II . Moderate to Large Class I Direct Composite Restorations : Cavity design : 1.Moderate to large direct class I restorations will typically feature flat walls that are perpendicular to occlusal forces . 2.If the occlusal portion of the restoration is expected to be extensive , elongated pear cutting instruments with round features are preferred because they result in strong ,90 degree cavosurface margins .

96. Clinical Technique : Step 1 : The tooth is entered in the area most affected by caries ,with the elongated pear diamond or bur positioned parallel to the long axis of the crown . Step 2 : The pulpal floor is prepared to an initial depth that is approximately 0.2 mm internal to the DEJ .

97. Step 3 : The mesial , distal ,facial and lingual extensions are dictated by the caries ,old restorative material ,or defect, always using the DEJ as a reference for both extensions and a pulpal depth . Step 4 : Extensions into marginal ridges should result in at atleast 1.5mm of remaining tooth structure for premolars and 2mm for molars .

98. Step 5 : If extensions is required toward the cusp tips ,the same depth that is approximately 0.2mm inside the DEJ is maintained ,usually resulting in the pulpal floor rising occlusally .

99. Step 6 : If extension is required towards facial or lingual groove radiating from the occlusal surface .When the groove extension is through the cusp ridge ,the instruments prepares the facial portion of the faulty groove at an axial depth of 0.2 mm inside the DEJ and gingivally to include all caries and other defects .

100. Step 7 : After extending the outline form to sound tooth structure , if any caries or old restorative material remains on the pulpal floor , it should be removed with the appropriately –sized round bur or hand instrument .

101. RESTORATIVE TECHNIQUE Placement of the adhesive : Step 1: The proximal surface of the adjacent should be protected from inadvertent etching by placing a Mylar strip or a Teflon tape. Step 2 : 37 % Phosphoric acid gel etchant is applied for 10 sec to all of the prepared tooth structure ,approximately 0.5mm beyond the prepared margins onto the adjacent unprepared tooth .

102. Step 3 : The area is rinsed thoroughly with the water spray to remove the etchant . Step 4 : It is clinically recommended to ‘blot-dry’ the etched area with the help of a damp cotton pellet , or a disposable brush to remove the excess water .

103. Step 5 : If the bonding system combines the primer and the adhesive, as in a one bottle etch and rinse adhesive ,the solution is applied next on all of the tooth structure that has been etched with the help of a microbrush . Step 6 : The adhesive is gently air dried with the help of the chip blower to evaporate any solvent (acetone , alcohol or water ) then light activated for 10-15 seconds ,as directed by the manufacture .

104. INSERTION AND LIGHT ACTIVATION OF THE COMPOSITE The following factor taken into be consideration in order to minimize the polymerization shrinkage of the composite restoration : 1. BILAYERED (SANDWICH) TECHNIQUE : The use of an RMGI liner or a flowable composite liner may reduce the effects of polymerization shrinkage stress because of their favourable elastic modulus .

105. 1. RMGI liner : The advantage of using this are : It bonds to the dentin without opening the dentinal tubules ,reducing the potential for postoperative sensitivity . ii. It provides a better seal when used in cases where the preparation extends gingivally onto root structure because of its bond to dentin and potential for fluoride release .

106. 2 . Flowable composite liner : It also advocated as liners under posterior composite restorations . Its advantage is that it may reduce some of the negative effect of polymerization shrinkage because of their very favourable elastic modulus .

107. 2. COMPOSITE PLACEMENT TECHNIQUES : I . Incremental technique : It is important to place the composite incrementally to minimize the polymerization depth of cure and reduce the negative effects of polymerization shrinkage. The deep portions of the tooth preparation are restored first ,with increments of no more than 2 mm in thickness .

108. ii . Anatomic layering technique : The anatomic references of the occlusal unprepared tooth structure should guide the placement and shaping of the composite increments using an anatomic layering technique . The ‘enamel layer’ of the restoration ,that is, the occlusal 1.5-3 mm ,is restored with this technique .

109. C . The operator places and light activates one increment cusp at a time and continues to place subsequent increments untill the preparation is filled and the occlusal anatomy is fully developed .

110. 3. CONFIGURATION FACTOR : The term configuration factor or c-factor has been used to describe the ratio of bonded to unbonded surfaces in a tooth preparation and restoration . A typical class I tooth preparation will have a high C-factor of 5 (five bonded surfaces –pulpal ,facial , lingual ,mesial and distal-vs.one unbonded surface –occlusal .

111. CONTOURING AND POLISHING OF THE COMPOSITE Contouring and polishing instruments should be used according to the specific surface being contoured and polished . Special fine diamond finishing instruments,12-bladed carbide finishing disks can be used to obtain excellent results .

112. Step 1 : A flame shaped carbide finishing bur or diamond is recommended for removing excess composite on facial surfaces . Medium speed with light intermittent brush strokes and air coolant is used for contouring .

113. Step 2 : Excess lingual composite is removed using a round or oval –shaped 12-bladed carbide finishing bur or finishing diamond . A smoother surface is produced using a finer round or oval carbide finishing bur (with 18-24 blades or 30-40) or fine diamond at medium speed with air coolant and light intermittent pressure .

114. Step 3 : Abrasives disks mounted on a mandrel specific to the disk type ,in a contra-angle hand piece at low speed ,can be used instead of or after the finishing bur or diamond in facial surfaces and some interproximal and incisal embrassure .

115. Step 4 : A No.12 surgical blade mounted in a Bard-Parker handle is well suited for removing excess material from the gingival proximal area . This instrument is ideal for removing gingival overhangs .

116. Step 5 : Final polishing is achieved with rubber or silicone polishing instruments ,diamond impregnated polishers ,polishing disks,and polishing pastes . Step 6 : Further contouring and finishing of proximal surfaces can be completed with abrasives finishing strips .

117. Step 7 : Finally ,occlusion should be carefully checked in maximum intercuspation and eccentric movements by having the patient close on a piece of articulating paper and slide mandibular teeth over the restored area .

118. CLINICAL TECHNIQUE FOR CLASS II DIRECT COMPOSITE RESTORATIONS

119. Small class II direct composite restoration CAVITY DESIGNS : Conservative designs : These preparations are less specific in form , having a scooped out appearance without a uniform or flat pulpal or axial walls.

120. Clinical techiques : A small round or elongated pear diamond or bur with round features may be used for this preparation to scoop out the carious or faulty material from the occlusal and proximal surfaces . The pulpal ad axial depths are dictated only by the depth of the lesion and are not uniform . The proximal extensions are likewise dictated only by the extent of the lesion but may require the use of another instrument with straight sides to prepare walls that are 90 degrees or greater .

121. 2. BOX ONLY DESIGN : This design is indicated when only the proximal surface is defective ,with no lesions on the occlusal surface .

122. Clinical technique : A proximal wall is prepared with a small elongated pear or round instrument ,held parallel to the long axis of the tooth crown . The instrument is extended through the marginal ridge in a gingival direction . The form of the box depends on which the instrument shape is used –the more box like with the elongated pear and the more scooped with the round. The facial,lingual and gingival extensions are dictated by the caries or defect .

123. 3. SLOT DESIGN : This design is indicated when the operators believed that access to the proximal lesion can be obtained from either a facial direction or a lingual direction rather than through a marginal ridge in a gingival direction .

124. Clinical technique : 1 . A small round diamond or bur is used to gain access to the lesion . 2. The instrument is oriented at the correct occluso -gingival position ,and entry is made with the instrument as close to the adjacent tooth as possible , preserving as much of the facial or lingual surface as possible .

125. 3. The preparation is extended occlusally , and gingivally enough to remove the lesion . The axial depth is determined by the extent of the lesion . 4. The occlusal, facial and gingival cavosurface margins are 90 degrees or greater .

126. MODERATE TO LARGE CLASS II DIRECT COMPOSITE RESTORATIONS It include an occlusal step and proximal box . Occlusal step Step 1 : A No. 330 or No.245 shaped diamond or bur is used to enter the pit next to the carious proximal surface .

127. The instrument is positioned parallel with the long axis of the tooth crown . If only one proximal surface is being restored , the opposite marginal ridge dentinal support should be maintained .

128. Step 2 : The pulpal floor is prepared with the instrument to a depth that is approximately 0.2mm inside the DEJ . The pulpal floor is relatively flat in a faciolingual plane but may rise and fall slightly in a mesiodistal plane . If caries remains in dentin ,it is removed after the preparation outline ,including the proximal box extensions ,has been established .

129. Step 3: The occlusal extension towards the proximal surface is prepared as conservatively as possible . The instruments extends through the marginal ridge to within 0.5 mm of the outer contour of the marginal ridge . This extension exposes the proximal DEJ and protects the adjacent tooth .

130. 2. Proximal step Extent of proximal box : The facial, lingual ,and gingival extensions of the proximal box of the preparation is determined by : The extent of the caries lesion Amount of old restorative material.

131. The two clinical possibilities are the following : Proximal box within the contact : If all of the defect can be removed without extending the proximal preparation beyond the contact , however , the restoration of the proximal contact with the composite is simplified .

132. 2 . Proximal box beyond the contact : Although it is not required to extend the proximal box beyond contact with the adjacent tooth . It may simplify the preparation , matrix placement and contouring procedures .

133. Clinical technique : Step 1: The proximal ditch cut is initiated with the instrument held over the DEJ to create a gingivally directed cut that is 0.2mm inside the DEJ . Step 2: The faciolingual cutting motion follows the DEJ and is usually in a slightly convex arc outward . During this entire cutting ,the instrument is held parallel to the long axis of the tooth crown .

134. Step 3 : The gingival floor is prepared flat with an approximately 90 degree cavosurface margin. Gingival extension should be as minimal as possible ,in an attempt to maintain an enamel margin . The axial wall should be 0.2 mm inside the DEJ and have a slight outward convexity .

135. Important clinical considerations : For large caries lesions , additional axial wall caries excavation may be necessary later ,during final tooth preparation . 2. No bevels are placed on the occlusal cavosurface margins .Bevels are not recommended on any of the proximal box walls and neither along the gingival margins of the proximal box .

136. 3 . If the gingival floor is on the root surface (no enamel at the cavosurface margin ),the use of a glass ionomer material may decrease microleakage and recurrent caries . 4 . A calcium hydroxide liner is indicated , however, to treat a near exposure of the pulp (within 0.5mm of the pulp) , a possible microexposure or an actual exposure.

137. RESTORATIVE TECHNIQUE : Matrix Application and Placement of the Adhesive : 1.After the operator cleans the teeth ,administers local anesthetics ,selects the shade of composite ,and isolates the area ,a wedge is placed in the gingival embrassure . 2.Early wedging helps in the seperation of teeth ,to compensate later for the thickness of the matrix band .

138. 3. Generally,the matrix is applied before adhesive placement . 4. An ultra thin metal matrix band generally is preferred for the restoration of a class II composite because it is thinner than a typical metal band and can be contoured better than a clear polyester matrix . 5. A Tofflemire -type matrix can be used for restoring in two surface tooth preparation .However, the precontoured sectional matrix strip explained in the following section is preferred .

139. 6. When both proximal surfaces are involved ,a Tofflemire retainer with an ultrathin (0.001 inch ), burnishable matrix band is used .The band is contoured , positioned , wedged , and shaped , as needed , for proper proximal contacts and embrassures . 9

140. Insertion and Light-activation of the Composite It is best to restore the proximal box portion of the preparation first . It is important to place the composite incrementally to maximize the curing potential and to reduce the negative effects of polymerization shrinkage .

141. Oblique incremental technique : 1 .This is the recommended technique for restotation the proximal box . 2. The first increment(s) should be placed along the gingival floor and should extend slightly up the facial (or lingual) wall .This increment should be only approximately 1-2 mm thick because it is the farthest increment from the curing light and the most critical in establishing a proper gingival seal .

142. 3. A second increment is then placed against the lingual (or facial ) wall , to restore about two thirds of the box . 4. The final increment is then placed to complete the proximal box and develop the marginal ridge . Subsequent additions , if needed, are made and light activated untill the proximal box is fully restored .

143. Contouring and Polishing of the Composite : The occlusal surface is shaped with a round or oval, 12-bladed carbide finishing bur or finishing diamond . Excess composite is removed at the proximal margins and embrassures with a flame-shaped,12-bladed carbide finishing bur or finishing diamond and abrasive disks .

144. 3. Any overhangs at the gingival area removed with a No.12 surgical blade mounted in a Bard-Parker handle with light shaving strokes to remove the excess . 4. Narrow finishing strips may be used to smooth the gingival proximal surface . 5. The occlusion is evaluated for proper contact. Further adjustments are made ,if needed ,and the restorations are finished with appropriate polishing points, cups, brushes, or disks .

145. Extensive Class II Direct Composite Restorations and Foundations Indications : Due to economic factors that prevent the patient from selecting a more expensive indirect restoration . 2. As a foundation restoration for indirect restorations when the operator determines that insufficient natural tooth structure remains to provide adequate retention and resistance from for the crown .

146. 3. As an interim restoration while waiting to determine the pulpal response or whether or not the restoration will function appropriately .

147. Clinical Considerations The primary differences for these very large preparations include the following : Some or all of the cusps may be capped . Extensions in most directions are greater . Secondary retention features are used. More resistance form features are used . Retention form for foundations must be placed far enough inside the DEJ to remain after the crown preparation is done subsequent .

148. CLASS VI DIRECT COMPOSITE RESTORATIONS

149. INDICATIONS : One of the most conservative indications for a directly placed posterior composite is a small faulty developmental pit located on a cusp tip .

150. Clinical Procedures : The typical class VI tooth preparation should be as small in diameter and as shallow in depth as possible . 2. The faulty pit is entered with an appropriate round bur or diamond oriented perpendicular to the surface and extended pulpally to eliminate the lesion .

151. 3. Visual examination and probing with an explorer often reveal that the fault is limited to enamel because the enamel in this area is quite thick . 4. Stains that appear through the translucent enamel should be removed ;otherwise , they may be seen after the composite restoration is completed .

152. REFERENCES Sturdevant’s art and science of operative dentistry fifth edition. Operative dentistry modern theory and practice M.A. Marzouk.

153. THANK YOU