CLASS II CAVITY PREPARATION
CHARACTERISTICS

General Characteristics

• Smooth, rounded and flowing outline form
• Definite walls, floors and rounded line angles
• Flat and even pulpal and gingival floors
• Cavosurface margins at 90 degrees, with no unsupported enamel

Occlusal Aspect Principles

• Outline form extends and follows to all susceptible grooves and fissures
• Isthmus width: 1mm width
• Remaining Marginal Ridge – Premolar: 1mm, Molar: 1.6mm
• 5mm Occlusal depth, around 1.75-2mm depth of walls
• Outline of proximal wall follows the external proximal surface
• Proximal walls show slight divergence
• Convergent buccal and lingual walls
• Buccal dovetail is longer, no sharp angles

Proximal Box:

• Convergent buccal/lingual walls
• Buccal and lingual walls extended to break contact
• Gingival clearance of 0.5mm, enough for the tip of the explorer to pass through
• Proximal clearance is visibly open or with a 0.3mm clearance, enough for the tip of the explorer to pass through
• Gingival floor width: MOLAR: 1.2-1.5mm, PREMOLAR: 1-1.2mm
• Gingival floor perpendicular to the long axis of the tooth (exception to lower first premolar)
• Axial wall follow the external outline of the tooth
• Axial wall is slightly divergent: for convenience form
• Bevelled axiopulpal line angle
• Bevelled gingival floor
• Reverse S-curve
• 90 degree exit angle

Treatment Management

• No damage to adjacent tooth/teeth or can be removed with polishing without adversely altering the shape of the contour
• No damage to simulated gingiva

Class II Cavity Preparation

Outline Form:

1. Fishtail/Dovetail – Location and Width
2. Isthmus – Location and Width
3. Remaining Marginal Ridge
4. Extension – Buccal & Lingual

Resistance Form:

1. Definite Walls/Line Angles
2. Pulpal Floor:
   1. Depth
   2. Flatness (Even depth all throughout)
3. Gingival Floor
   1. Width
   2. Flatness
   3. Depth
4. S-curve
5. Bevel of Axiopulpal Line Angle
6. Cavosurface Margin (Even, smooth)

Retention Form:

1. Convergence of Bu/Li Walls
   1. Occlusal
   2. Proximal Box
2. Retention Grooves

Convenience Form

1. Clearance form Adjacent Tooth
   1. Buccal
   2. Lingual
   3. Gingival

Finishing of Walls and Margins

1. Smoothness
2. Absence of Unsupported Enamel
3. Rounded junctions between Walls

Class II Filling

1. Functional Anatomy
   1. Marginal Ridge
   2. Pits and Grooves
   3. Cuspal Inclinations
   4. Embrasure Form and Proximal Contour
2. Proximal Contact
3. Marginal Integrity
4. Smoothness

Proximal Reduction

• Taper
• Condition of the Adjacent tooth
• Clearance
• Finish

Incisal / Occlusal Reduction

• Anatomic Form
• Clearance
• Finish

Buccolingual/Labiolingual Reduction

• Occlusal Convergence
• Anatomic Form
• 2-Phase Reduction (Anterior)
• Finish

Cervical Preparation

• Continuity and Width
• Location and Height of the Preparation
• Gingival Condition and Health
• Finish

Parallelism

• Path of Insertion