Clinicians should proceed with great caution when placing two implants adjacent to each other in the esthetic zone. In most cases, only 2, 3, or 4 mm of soft tissue height (average 3.4 mm) can be expected to form over the interimplant crest of bone. These results showed that modification of treatment plans may be necessary when esthetics are critical for success.

13 teeth in block were extracted from 2 patients. Their facial periodontal condition was essentially within normal clinical limits. Temporary crowns covering the bevel were placed below the base of the crevice 1 to 8 weeks prior to extraction. At time of extraction, all blocks were decalcified, the temporary crown dissolved, and the blocks prepared for histologic examinations using buccolingual cut, step serial sections. Histologic data revealed reformation of a new supracrestal attachment unit within 1 week following crown placement. The reformation of the gingival unit consisted of marginal recession with apical and lateral migration of the junctional epithelium to the level of remaining cementum inserted fibers. With gingival recession and migration of junctional epithelium, resorption of crestal portions of the facial plate occurred. However, periodontal fibers anchored into cementum opposite the resorbed bone were not lysed. Rather, the attached fibrillar ends appeared to interdigitate with fibers from the corium of the facial gingiva at this site, thereby forming a more apically located crestal attachment. This response may be one mechanism of reformation of the gingival attachment unit taking place following mechanical and/or surgical injury to this site and is completed often, within 2 weeks after injury.

Four human teeth and their facial gingival attachment were removed en block 3 months after periodontal flap therapy and citric acid root conditioning and then prepared for histologic evaluation. At the time of periodontal surgery, and prior to citric acid application, the facial root surface was grooved at midline and citric acid was applied only to one-half of each root surface. Tissues were decalcified and histologically prepared as horizontally oriented, step serial sections from the level of the gingival margin to the level of the facial crest. The gingival margins demonstrated reformation of a crevice. The corium at this level showed a mild inflammatory infiltrate. Apical to this level, junctional epithelium adhered to both sides of the root surface and to the central groove. Further apically, supracrestal fiber groups were encountered. No new cementum was noted in these areas. Fiber attachment was present apical to this level. Since no new cementum was seen at this area of attachment, it may represent collagen attachment present prior to periodontal surgery. In the four specimens examined, no differences were seen in the soft tissue closures between the root-planed citric acid-treated root surfaces and root surfaces which received root planing alone.