Relative resistance of long junctional epithelial adhesions and connective tissue attachments to plaque-induced inflammation.

This study compared the resistance to periodontal disease of the long junctional epithelial adhesion and the naturally occurring dentogingival junction. Two groups were used, each containing three young male beagle dogs with all permanent teeth erupted. Periodontitis was induced around maxillary and mandibular premolars in the experimental dogs over a 42-day period, using subgingival ligatures and a soft diet. Fourteen days after ligature removal, flaps were reflected, granulation tissue was removed and the roots were planed to the alveolar crest. Reference grooves were placed in the root surfaces at the level of the alveolar bone, the flaps were positioned over the alveolar crests, and sutures were placed. A 60-day period permitted healing with formation of long junctional epithelial adhesions. During this 116-day period control dogs were maintained in gingival health by daily brushing and by prophylaxis every 14 days. Both groups had a high level of health (GI scores of 0) at the beginning of the 20-day combined disease phase. Inflammation was induced in both groups by subgingival ligature placement and a plaque-promoting diet. Right and left sides of both groups represented separate time intervals within the 20-day period. Block sections were secured at time of killing and the tissues were prepared for light and fluorescent microscopic evaluation. Mean GI scores and mean probing depths increased similarly in both groups. Tagge index scores of gingival inflammation were higher at the longer time periods in the experimental animals. However, they displayed an intact long junctional epithelial adhesion throughout the study, while control animals frequently showed ulceration of the sulcular epithelium. Neither group showed significant changes in location of the apical cells of the attachment epithelium. Crestal osteoblastic activity, confirmed with Procion labeling, predominated in the experimental animals, while osteoclastic activity predominated in the control. Under the conditions of this study, there appeared to be no appreciable difference in resistance to disease between a long junctional epithelial adhesion and a true connective tissue attachment.