Cavity Classification and Preparation Quiz

Cavity Classification

• Class I: Developmental cavities found in pits and fissures on occlusal surfaces of posterior teeth, molars' buccal or lingual pits, and lingual pits of maxillary incisors.
• Class II: Cavities located on the proximal surfaces of posterior teeth.
• Class III: Cavities affecting interproximal surfaces of anterior teeth.
• Class IV: Similar to Class III but also involves the incisal edge of anterior teeth.
• Class V: Cavities on the cervical third of facial or lingual surfaces, often due to sweet consumption.
• Class VI: Not part of original classifications; identifies cavities on incisal or occlusal surfaces due to abrasion.

Cavity Types

• Simple Cavity: Involves one tooth surface.
• Compound Cavity: Involves two surfaces of a tooth.
• Complex Cavity: Involves three or more surfaces of a tooth.

Elements of Cavity Preparations

• Include outline form, resistance form, retention form, convenience form, finishing/refinement, and cleansing/debridement.
• All elements are essential during cavity prep.

Tooth Preparation Forms

• Builds walls, lines, and angles in the cavity.

Walls of Cavity Preparation

• Defined as sides or floors of the cavity, named after adjacent tooth surfaces:
  • Axial Wall: Runs parallel to the tooth's long axis.
  • Pulpal Wall: Also known as the pulpal floor, is perpendicular to the long axis.
  • Gingival Wall: Nearest to the gingiva, perpendicular to the long axis.
• Internal Wall: Does not extend to external tooth surfaces.
• External Wall: Extends to the tooth's external surface, named by the surface it involves.

Cavity Structure

• Line Angles: Junctions of two walls in cavity prep.
• Point Angles: "Corners" formed by the junction of three walls.
• Cavosurface Margin: Angle formed where cavity walls meet unprepared tooth surface; critical for preventing leakage.

Cavity Preparation Forms

• Outline Form: Overall shape determined by decay extent and restorative material, stays within cavosurface margin.
• Resistance Form: Internal shape protects from masticatory stresses; involves shape and placement of walls.
• Retention Form: Shape that retains restoration; often includes undercutting walls for mechanical locking in amalgam preparations.
• Convenience Form: Access form necessary for instrumentation and restoration placement, often expanding beyond outline form.

Removal of Carious Dentin

• Involves cutting tooth structure using instruments like enamel hatchets, chisels, and spoon excavators.

Final Cavity Preparation Steps

• Finishing/Refinement: Final planning of cavity walls before restoration.
• Cleansing/Debridement: Removal of debris through spraying and rinsing, typically using high-volume evacuation and air/water syringes.