Operative Dentistry (Fundamentals of tooth preparation)

TOOTH PREPARATION TERMINOLOGY
 A termed simple if only one tooth surface is involved, compound if two surfaces are involved, and complex if a
preparation involves three or more surfaces
ABBREVIATED DESCRIPTIONS OF TOOTH PREPARATIONS
 Tooth preparation is abbreviated by using the first letter, capitalized, of each tooth surface involved,
O = Occlusal tooth preparation
MO = Mesial and Occlusal surfaces
MOD = Mesial, Occlusal, and Distal Surfaces
TOOTH PREPARATION WALLS
INTERNAL WALL
 The prepared surfaces that does not extend to the external tooth surfaces
- Pulp and Axial
AXIAL WALL
 The internal wall parallel to the long axis of the tooth
PULPAL WALL (FLOOR)
 The internal wall that is perpendicular to the axis of the tooth and occlusal of the pulp.
EXTERNAL WALL
 The prepared surface that extends to the external tooth surface.
 A wall takes the name of the tooth surface that the wall is adjacent to
1. FLOOR (SEAT)
- The prepared wall that is reasonably horizontal and perpendicular to the occlusal forces that are
directed occlusogingivally.
- Pulpal and gingival floors.
- This preparation feature increases the resistance form of the restored tooth against post-
restorative fracture.
2. ENAMEL WALL
- Portion of a prepared external wall consisting of enamel
-
3. DENTINAL WALL
- Portion of a prepared external wall consisting of dentin, in which mechanical retention features
may be located

TOOTH PREPARATION ANGLES
 The junction of two or more prepared surfaces is referred to as angle
 The junction is almost always “softened” so as to present a slightly rounded configuration.
1. LINE ANGLE – the junction of two planar surfaces of different orientation along a line.
- Internal line angle is line angle whose apex points into the tooth
- External line angle is the line angle whose apex points away from the tooth
2. POINT ANGLE – the junction of three planar surfaces of different orientation

CAVOSURFACE ANGLE AND CAVOSURFACE MARGIN
 The angle of tooth structure formed by the junction of a prepared wall and the external surface of the tooth.
 The actual junction I referred to as cavosurface margin
 Carvosurfac angle differ with the location on the tooth, the direction of the enamel rods on the prepared wall,
or the type of restorative material be used