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CLASS IICLASS IICLASS IICLASS II(pp(pp(pp(pp 658658658658----664664664664,,,, 696696696696----708708708708))))
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Seven Steps of Cavity PreparationSeven Steps of Cavity PreparationSeven Steps of Cavity PreparationSeven Steps of Cavity Preparation
1) Establish the outline form2) Establish resistance form
3) Establish retention form
4) Provide convenience form
5) Removal of remaining caries
6) Finish the cavity walls andmargins
7) Toilet of the cavity preparation
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StepStepStepStep 1111
Outline Form Outline Form Outline Form Outline Form Considerations
– Visualize outline pre-operatively – Gentle sweeping curves - “fluidity”
– Remove undermined enamel
– Extend for preventionMargins on smooth surfaces and self
cleansing accessible areas
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StepStepStepStep 1111
Outline Form Outline Form Outline Form Outline Form Preparation shape
Encompasses carious lesion and caries
susceptible areas
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Ideal PreparationIdeal PreparationIdeal PreparationIdeal Preparation
Fishtail versus dovetail
Dovetails parallel ridges
Outline follows fissures
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StepStepStepStep 1111
Outline Form Outline Form Outline Form Outline Form Considerations
– Visualize outline pre-operatively
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StepStepStepStep 1111
Outline Form Outline Form Outline Form Outline Form Considerations
– Gentle sweeping curves - “fluidity”
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StepStepStepStep 1111
Outline Form Outline Form Outline Form Outline Form Considerations
– Gentle sweeping curves - “fluidity”
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StepStepStepStep 1111
Outline Form Outline Form Outline Form Outline Form Considerations
– Remove undermined enamel
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StepStepStepStep 1111
Outline Form Outline Form Outline Form Outline Form
Considerations
– Extend for prevention Margins on smooth surfaces and self cleansing accessible areas
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StepStepStepStep 1111
Outline Form Outline Form Outline Form Outline Form
Considerations
– Extend for prevention Margins on smooth surfaces and self cleansing accessible areas
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Class II Outline Form Class II Outline Form Class II Outline Form Class II Outline Form
Smooth flowing outline (occlusal view)
Include carious pits/fissures and non-coalesced areas (extension for
prevention) Include all of the proximal contact area
90° “exit angles” (occlusal view of box)
Follow tooth contours (proximal view)
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Rounded proximal
Flat proximal contour
BUCCOPROXIMAL WALLand
LINGUOPROXIMAL WALL
- are straight and flat to theaxial wall
- exits 90° at cavosurface
- blend into the isthmus,
preserving the cusps- may or may not use an
“s-curve”
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Rounded proximal Flat proximal contour
S-curve: Transition from proximal wall to buccalor lingual walls; used only as needed
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Class II Outline FormClass II Outline FormClass II Outline FormClass II Outline Form ---- Proximal ExtensionsProximal ExtensionsProximal ExtensionsProximal Extensions
Remove proximalcontact area and
extend the gingival wallto provide 0.5 mm fromthe adjacent tooth
Include all enamel caries and extend forprevention to caries-susceptible areas
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Class II Outline FormClass II Outline FormClass II Outline FormClass II Outline Form
Proximal ExtensionsProximal ExtensionsProximal ExtensionsProximal ExtensionsBuccal and lingual walls are extended,
following adjacent tooth contours, to
provide 0.3 - 0.5 mm clearance
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RGS 1 10-7-14 Hatchet
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Class II Outline FormClass II Outline FormClass II Outline FormClass II Outline Form
Proximal ExtensionsProximal ExtensionsProximal ExtensionsProximal ExtensionsExtensions follow proximalcontours and allow access
for:
finishing and polishing torefine margins
brushing & flossing toreduce caries recurrence
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StepStepStepStep 2222
Resistance Form Resistance Form Resistance Form Resistance Form Flat walls (pulpal, gingival)
Restricted extension(conserve tooth structure)
Adequate bulk (of restorative material)
Failure of resistance form
– Fractured restoration
– Fractured tooth
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StepStepStepStep 2222
Resistance Form Resistance Form Resistance Form Resistance Form Flat walls (pulpal, axial, gingival, etc.)
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StepStepStepStep 2222
Resistance Form Resistance Form Resistance Form Resistance Form Restricted extension = conserve tooth structure
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StepStepStepStep 2222
Resistance Form Resistance Form Resistance Form Resistance Form Restricted extension = conserve tooth structure
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StepStepStepStep 2222
Resistance Form Resistance Form Resistance Form Resistance Form Restricted extension = conserve tooth structure
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StepStepStepStep 2222
Resistance Form Resistance Form Resistance Form Resistance Form Restricted extension
Preserve bulk of marginal ridge
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StepStepStepStep 2222
Resistance Form Resistance Form Resistance Form Resistance Form Adequate bulk (of restorative material)
StStStSt 2222
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StepStepStepStep 2222
Resistance Form Resistance Form Resistance Form Resistance Form
Failure of resistance form
– Fractured restoration – Fractured tooth
Cl II R i FCl II R i FCl II R i FCl II R i F
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Class II Resistance Form Class II Resistance Form Class II Resistance Form Class II Resistance Form
1. Flat pulpal wall
2. 1.5 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” followsenamel rods
1
2
3
4
5
6
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Errors in the Proximal Box Errors in the Proximal Box Errors in the Proximal Box 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
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Class II Resistance Form Class II Resistance Form Class II Resistance Form Class II Resistance Form
90-degree to tangent at cavosurface,
“s-curve,” and smooth flowing outline
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Preparing thePreparing thePreparing thePreparing theproximal box proximal box proximal box proximal box
1. Envision box with ideal0.4 mm clearance at proximal
extensions (0.3 - 0.5 mm)
2. Use bur to establish boxform, undermining enamelrods near ideal proximalextensions
0.4 mm
0.4 mm
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Refining the proximal wallsRefining the proximal wallsRefining the proximal wallsRefining the proximal walls
3. Use hatchet or GMT to remove
undermined enamel rods to idealextension to buccoproximal, linguo-proximal, and gingival (0.5 mm) walls
Note that
underminedenamel rods are
subject to failure!
0.5 mm
StepStepStepStep 3333
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StepStepStepStep 3333
Retention Form Retention Form Retention Form Retention Form
Mechanical undercuts and locks
Accessory forms
– Grooves, coves
– Slots, potholes
– Pins
StepStepStepStep 3333
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StepStepStepStep 3333
Retention Form Retention Form Retention Form Retention Form Mechanical undercuts and locks
StepStepStepStep 3333
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StepStepStepStep 3333
Retention Form Retention Form Retention Form Retention Form Accessory forms
– Grooves, coves
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Class II Retention Form Class II Retention Form Class II Retention Form Class II Retention Form
To preventocclusaldisplacement
– Convergence ofbuccal and lingualwalls of occlusal
– Convergence ofbuccoproximal andlinguoproximal walls
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Class II Retention Form Class II Retention Form Class II Retention Form Class II Retention Form
To prevent proximal displacement – Dovetail and buccal and lingual extensions
StepStepStepStep 3333
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StepStepStepStep 3333
Retention Form Retention Form Retention Form Retention Form Accessory forms
– Grooves, coves
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Class II Retention Form Class II Retention Form Class II Retention Form Class II Retention Form To prevent proximal
displacement – Retention grooves at
axiobuccal and axiolingual
line angles
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Retention GroovesRetention GroovesRetention GroovesRetention Grooves
must be in dentin
are extensions of theaxial wall
follow curvature ofaxial wall & DEJ
StepStepStepStep 4444
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StepStepStepStep 4444
Convenience Form Convenience Form Convenience Form Convenience Form
Adequate observation
Accessibility
Ease of operation
StepStepStepStep 4444
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StepStepStepStep 4444
Convenience Form Convenience Form Convenience Form Convenience Form Adequate observation
StepStepStepStep 4444
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StepStepStepStep 4444
Convenience Form Convenience Form Convenience Form Convenience Form Accessibility
StepStepStepStep 4444
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StepStepStepStep 4444
Convenience Form Convenience Form Convenience Form Convenience Form Ease of operation
Class II Convenience FormClass II Convenience FormClass II Convenience FormClass II Convenience Form
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Class II Convenience Form Class II Convenience Form Class II Convenience Form Class II Convenience Form
Axial wall diverges fromproximal surface
Adequate isthmus width for condensation
Cl II I i FCl II I i FCl II I i FCl II I i F
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Class II Inconvenience Form Class II Inconvenience Form Class II Inconvenience Form Class II Inconvenience Form
Axial wall converges with
proximal surfaceDoes not allow for proper
condensationAxiogingival line angleapproaches pulp
StepStepStepStep 5555
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Removing Caries Removing Caries Removing Caries Removing Caries Caries Removal
Removal of decalcified enamel anddentin
Considerations
– Arrest caries process – Solid foundation
– May modify outline, resistance and
retention
StStStSt 5555 R l f C iR l f C iR l f C iR l f C i
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StepStepStepStep 5555: Removal of Caries: Removal of Caries: Removal of Caries: Removal of Caries
Proper outline,
resistance,retention, andconvenience forms
will result inproviding properaccess for
revealing andremoval of allremaining caries
StStStSt 6666
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StepStepStepStep 6666
Finishing Enamel Walls and Margins Finishing Enamel Walls and Margins Finishing Enamel Walls and Margins Finishing Enamel Walls and Margins Create the best marginal seal
Enhance all preparation principles
Finishing the CavityFinishing the CavityFinishing the CavityFinishing the Cavity
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Walls and MarginsWalls and MarginsWalls and MarginsWalls and Margins
Plane proximal and axial walls
Place gingival bevel with gingival margin trimmer
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StepStepStepStep 7777
Perform Toilet of the Cavity Perform Toilet of the Cavity Perform Toilet of the Cavity Perform Toilet of the Cavity
Clean all walls and margins
Remove all debris
Wash and dry, but DO NOT DESICCATE!
Final inspection