Restorative margins and periodontal health: a new look at an old perspective.

The indiscriminate placement of the margins of dental restorations into the gingival crevice for the purpose of esthetics or protection from decay can no longer be considered good practice. The junctional epithelium and the supracrestal fibers, together, have been called the biologic width, which is considered to have a length of 2 mm. A more accurate term for the biologic width, one that expresses the function and diversity of the component tissues while avoiding reference to dimension, is the "subcrevicular attachment complex." The most accurate anatomic structure from which to take measurements for margin placement is the healthy, stable gingival margin. It is clinically visible, unlike the biologic width, and should replace the latter as the landmark of choice for placing dental margins. Surgical crown lengthening will be necessary when restorations will end at or below the alveolar crest.