Bucco-Lingual Contour of the Restoration

Abstract

The bucco-lingual contour of the restoration plays an important role in maintaining health of periodontal tissue. There were numerous articles concerning axial contours and those may be divided into two groups including the normal contour and under contour. The former was based on the theory of protecting gingiva from mechanical injury, and the latter was based on the theory of self-cleansing. The theory of gingival protection has been advocated in many textbooks with little scientific evidence. The theory of self-cleansing is supported by experimental evidence that plaque is the primary etiology in periodontal disease.
Though the axial contour consists of supragingival and subgingival portions, many articles were only concerned with supragingival contour. The majority of these articles reported that the less convexity of supragingival contour accumulated less plaque at the cervical region. And other articles reported that such less convexity increased the stimulation to the gingival margin during mastication, but did not produce any significant changes in healthy gingiva. The food often reaches to the gingival margin of the axial surfaces on the side of functional cusp (upper lingual and lower buccal surfaces) . So, those surfaces should be shaped normal or less contour.
On the other hand, the degree of the subgingival convexity, which is more important to the gingival health than the supragingival one because of the proximity to the internal surface of free gingiva, is rarely reported. The subgingival convexity of the crown should not be made over-contoured so as not to congest the free marginal gingiva or tear its periodontal fibers.