64 Theories and techniques of oral implantology

Fig. 3-19. Here the gingival sulcus is located on the cementum. Normally this is found in late stages of passive eruption. (From Gottlieb, B.: J.A.D.A. 14:2178, 1927.)

Fig. 3-20. The relationship of the epithelial cuff and the dentogingival junction shown in the far stages of passive eruption. (Redrawn from Sicher, H., editor: Orban's oral histology and embryology, ed. 6, St. Louis, 1966, The C. V. Mosby Co.)

of the tooth becomes exposed. This phase tends to cause somewhat uneven exposure of the tooth. The gingival sulcus may be considerably higher on one side of the tooth than on the other (Fig. 3-18). The recession of the gingiva may continue until not only all of the enamel crown but also the uppermost parts of the cementum are exposed (Fig. 3-19) .

The apical shifting of the dentogingival junction is related to the shifting of the epithelial cuff (Fig. 3-20). This cuff, in order to be functional, must be at least 0.25 to 6 mm. thick. As the epithelial cuff migrates downward, it maintains a certain minimal thickness by proliferation. As long as this proliferation is correlated with active eruption and attrition, it is normal. Otherwise, it is pathologic.

It was formerly thought that the epithelial cuff was not attached to the surface of the tooth but closely bound to it by the turgor of the connective tissue elements. It is now known that on the erupted