Human gingival attachment responses to subgingival crown placement. Marginal remodelling

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.