Introduction
Class V cavities (Black's classification) are cavities in the gingival third of the facial (labial, buccal) or lingual (palatal) surface of any tooth that do not start in a pit. Most are carious, often on the root; non-carious cervical lesions (abrasion, erosion, abfraction) are restored with the same designs. This note compares the conventional configuration for amalgam, held by mechanical retention, with the conservative configuration for adhesive materials, which saves tooth tissue and relies on bonding.
The cervical area and the outline
In the cervical third enamel is thin and ends at the cementoenamel junction (CEJ), the gingival margin often lies on cementum or root dentin, the pulp is close, and gingival fluid and bleeding hinder moisture control.
In both configurations the outline is dictated by the lesion: all carious or defective tissue is included and nothing more – there is no extension for prevention.
- Shape: usually kidney (bean) or crescent shaped. The gingival margin follows the curve of the gingiva and CEJ (convex towards the root) and the occlusal (incisal) margin runs roughly parallel to it. Small lesions give an oval outline.
- Margins on sound tooth, in smooth curves; mesial and distal ends rounded.
- The gingival margin is placed at or above the gingival crest whenever the lesion allows; a subgingival margin needs gingival retraction.