روپ قداص رتکد ناشخرد یاھدادعتسا رتفد

Transcription

1 CLASS II (pp , ) دکتر صادق پور دفتر استعدادھای درخشان

2 Seven Steps of Cavity Preparation 1) Establish the outline form 2) Establish resistance form 3) Establish retention form 4) Provide convenience form 5) Removal of remaining caries 6) Finish the cavity walls and margins 7) Toilet of the cavity preparation

3 Step 1 Outline Form Considerations Visualize outline pre-operatively Gentle sweeping curves - fluidity Remove undermined enamel Extend for prevention Margins on smooth surfaces and self cleansing accessible areas

4 Preparation shape Step 1 Outline Form Encompasses carious lesion and caries susceptible areas

5 Ideal Preparation Outline follows fissures Dovetails parallel ridges Fishtail versus dovetail

6 Step 1 Outline Form Considerations Visualize outline pre-operatively

7 Step 1 Outline Form Considerations Gentle sweeping curves - fluidity

8 Step 1 Outline Form Considerations Gentle sweeping curves - fluidity

9 Step 1 Outline Form Considerations Remove undermined enamel

10 Step 1 Outline Form Considerations Extend for prevention Margins on smooth surfaces and self cleansing accessible areas

11 Step 1 Outline Form Considerations Extend for prevention Margins on smooth surfaces and self cleansing accessible areas

12 Class II Outline Form Smooth flowing outline (occlusal view) Include carious pits/fissures and noncoalesced areas (extension for prevention) Include all of the proximal contact area 90 exit angles (occlusal view of box) Follow tooth contours (proximal view)

13 BUCCOPROXIMAL WALL and LINGUOPROXIMAL WALL Flat proximal contour - are straight and flat to the axial wall - exits 90 at cavosurface - blend into the isthmus, preserving the cusps Rounded proximal - may or may not use an s-curve

14 S-curve: Transition from proximal wall to buccal or lingual walls; used only as needed Rounded proximal Flat proximal contour

15 Class II Outline Form - Proximal Extensions Include all enamel caries and extend for prevention to caries-susceptible areas Remove proximal contact area and extend the gingival wall to provide 0.5 mm from the adjacent tooth

16 Class II Outline Form Proximal Extensions This image cannot currently be display ed. Buccal and lingual walls are extended, following adjacent tooth contours, to provide mm clearance RGS Hatchet

17 Class II Outline Form Proximal Extensions This image cannot currently be display ed. Extensions follow proximal contours and allow access for: finishing and polishing to refine margins brushing & flossing to reduce caries recurrence

18 Step 2 Resistance Form Flat walls (pulpal, gingival) Restricted extension (conserve tooth structure) Adequate bulk (of restorative material) Failure of resistance form Fractured restoration Fractured tooth

19 Step 2 Resistance Form Flat walls (pulpal, axial, gingival, etc.)

20 Step 2 Resistance Form Restricted extension = conserve tooth structure

21 Step 2 Resistance Form Restricted extension = conserve tooth structure

22 Step 2 Resistance Form Restricted extension = conserve tooth structure

23 Step 2 Resistance Form Restricted extension Preserve bulk of marginal ridge

24 Step 2 Resistance Form Adequate bulk (of restorative material)

25 Step 2 Resistance Form Failure of resistance form Fractured restoration Fractured tooth

26 Class II Resistance Form Flat pulpal wall mm minimum pulpal depth (RGS 1) 3. Flat gingival wall (B-L) 4. Axial depth 1.0 mm min. (0.5 mm into dentin) 5. Rounded axiopulpal line angle 6. Gingival bevel follows enamel rods

27 Errors in the Proximal Box Avoid sharps corners, flared, and beveled walls - maintain proximal box at 1.0 mm axial depth with 90-degree cavosurface margins

28 Class II Resistance Form 90-degree to tangent at cavosurface, s-curve, and smooth flowing outline

29 Preparing the proximal box 0.4 mm 0.4 mm 1. Envision box with ideal 0.4 mm clearance at proximal extensions ( mm) 2. Use bur to establish box form, undermining enamel rods near ideal proximal extensions

30 Refining the proximal walls 0.5 mm 3. Use hatchet or GMT to remove undermined enamel rods to ideal extension to buccoproximal, linguoproximal, and gingival (0.5 mm) walls Note that undermined enamel rods are subject to failure!

31 Step 3 Retention Form Mechanical undercuts and locks Accessory forms Grooves, coves Slots, potholes Pins

32 Step 3 Retention Form Mechanical undercuts and locks

33 Step 3 Retention Form Accessory forms Grooves, coves

34 Class II Retention Form To prevent occlusal displacement Convergence of buccal and lingual walls of occlusal Convergence of buccoproximal and linguoproximal walls

35 Class II Retention Form To prevent proximal displacement Dovetail and buccal and lingual extensions

36 Step 3 Retention Form Accessory forms Grooves, coves

37 Class II Retention Form To prevent proximal displacement Retention grooves at axiobuccal and axiolingual line angles

38 Retention Grooves must be in dentin are extensions of the axial wall follow curvature of axial wall & DEJ

39 Step 4 Convenience Form Adequate observation Accessibility Ease of operation

40 Step 4 Convenience Form Adequate observation

41 Step 4 Convenience Form Accessibility

42 Step 4 Convenience Form Ease of operation

43 Class II Convenience Form Axial wall diverges from proximal surface Adequate isthmus width for condensation

44 Class II Inconvenience Form Axial wall converges with proximal surface Does not allow for proper condensation Axiogingival line angle approaches pulp

45 Step 5 Removing Caries Caries Removal Removal of decalcified enamel and dentin Considerations Arrest caries process Solid foundation May modify outline, resistance and retention

46 Step 5: Removal of Caries Proper outline, resistance, retention, and convenience forms will result in providing proper access for revealing and removal of all remaining caries

47 Step 6 Finishing Enamel Walls and Margins Create the best marginal seal Enhance all preparation principles

48 Finishing the Cavity Walls and Margins Plane proximal and axial walls Place gingival bevel with gingival margin trimmer

49 Step 7 Perform Toilet of the Cavity Clean all walls and margins Remove all debris Wash and dry, but DO NOT DESICCATE! Final inspection