62 Theories and techniques of oral implantology

the fully erupted tooth, one group   the gingivo-

dental   consists of fibers that radiate outward from
the cementum toward the crest of the gingival margin, toward the outer surface of the marginal gingiva, and toward the periosteum of the outer face of the alveolar crest, where they blend with the periosteum or terminate in the attached gingiva. Interproximally they extend toward the crest and central portion of the interdental gingiva. Another group, the circular group, has fibers that form rings around the tooth above the bony alveolar crest, passing through the connective tissue of the marginal and interdental gingiva. Fibers of the third group, the transseptal, run interproximally from the cementum of the tooth to the cementum of the neighboring tooth (Fig. 3-15). These fiber bundles lie between the gingival sulcus and the crest of the interdental bone and are sometimes classified as part of the periodontal ligament.

The gingival sulcus is a shallow groove that develops between the tooth and the gingiva as the tooth erupts (Fig. 3-16) . It may be demonstrated clinically by the careful insertion of the tip of a narrow, blunt probe. The sulcus is often less than

0.5 mm. deep, but a healthy sulcus may be as deep as 6 mm. However, generally the shallower the sulcus, the healthier the condition of the marginal gingiva.

The connective tissue at the base of the sulcus always contains lyrnphocytes and plasma cells. These are not indicative of a pathologic condition but rather represent a chronic low-grade inflammation. They are normal constituents of the sulcus, representing a chronic defensive reaction against bacterial activity and food decomposition.

The base of the gingival sulcus is the uppermost limit of the dentogingival junction. As this junction shifts toward the root, the sulcus naturally follows it. Thus the location of the sulcus on the tooth is directly related to the position of the dentogingival junction.

Dentogingival junction

The dentogingival junction, or area where the soft oral tissues join the hard dental tissues, protects the root of the tooth, periodontal ligament, and alveolar bone against chemical and bacterial invasion. It consists of two elements: a dense resilient

Free gingiva

Epithelial attachment to enamel

Epithelial attachment to cementum

Bottom of gingival sulcus

Enamel

Cementoenamel junction

Cementum

End of epithelial attachment

Fig. 3-17. At the end of active eruption, the gingival sulcus in a normal tooth is located on the tooth enamel. (From Gottlieb, B., and Orban, B.: Biology and pathology of the tooth [translated by M. Diamond], New York, 1938, The Macmillan Co.)