The implant site 73

inflammation of the gingiva. The gingiva changes color and becomes swollen, losing its stippled appearance. Neutrophilic leukocytes and proteolytic enzymes produced by bacteria bring about tissue de-generation. The gingival fibers of the periodontal membrane as well as local cementoblasts are destroyed, and no further formation of cementum is possible. The epithelial attachment increases in depth and its coronal portion separates from the tooth's surface, forming a distinct pocket (Fig. 3-30).

Chemical debris and more pathogenetic bacteria accumulate in the pocket and the inflammation spreads. When it reaches the alveolar crest, bone resorption begins. Unless treated by scaling and surgical removal of the periodontal pocket, periodontitis gradually leads to tooth loss by progressively destroying the alveolar crest (Fig. 3-31) .

The pattern of bone destruction depends on the location of the periodontal pocket. When the pocket is coronal to the alveolar crest—a suprabony pocket
   the bone gradually retreats under it (Fig. 3-32). This type of situation is most commonly seen in the anterior teeth.

When the pocket is infrabony or apical to the

Fig. 3-33. By its bone distribution pattern, the infrabony pocket creates deep crevices that invite further complications.

alveolar crest, that part of the crest bordering the pocket undergoes more rapid resorption (Fig. 3-33). Eventually, however, the entire crest maybe removed by the lateral spread of the inflammation or as a consequence of occlusal disharmony. Infrabony pockets usually occur in the interproximal areas of the bicuspids or on the buccal and lingual faces of the molars.

The alveolar crest may also resorb from degenerative changes within the periodontal tissues. The cause of this condition, periodontosis, is believed to be systemic, occurs more often in young adult females than in males, and usually involves the anterior maxillary teeth. In periodontosis there is no primary inflammation of the gingiva; the first sign is usually migration of the teeth. This results from the proliferation of granulation tissue in an area where the collagen fibers of the periodontal ligament have degenerated (Fig. 3-34) . The tissue increase

Fig. 3-34. As periodontosis develops, the collagenous fibers (CD) degenerate and granulation tissue (GT) forms in the area. The epithelial attachment (EA) grows apically. When it separates from the tooth it forms a sudden, deep pocket. (Redrawn from Bhaskar, S. N.: Synopsis of oral pathology, ed. 3, St. Louis, 1969, The C. V. Mosby Co.)