Healing following implantation of periodontitis-affected roots into gingival connective tissue

The aim of the present investigation was to examine if a new connective tissue attachment can be established on a previously periodontitis involved root surface, located in contract with gingival connective tissue during healing. A total of 28 teeth in one dog (beagle) and two monkeys (Macaca cynomolgus) were subjected to experimental periodontal tissue breakdown by placing cotton floss ligatures or orthodontic elastics around the teeth. The ligatures were left in situ until about 50% of the supporting tissues had been lost. Following resection of the crowns, the teeth were root filled and the exposed parts of the roots thoroughly scaled and planed. Each root was extracted and implanted into grooves prepared in edentulous areas of the jaws in such a way that the root was embedded to half its circumference in bone, leaving the remaining part to be covered by the gingival connective tissue of the repositioned flap of the recipient site. Root implantation and sacrifice of the animals were scheduled to allow for observation periods of 2 and 3 months of healing. An analysis of histologic specimens, obtained from biopsies of the recipient site tissues, disclosed that a new fibrous attachment failed to form on a previously "exposed" root surface located in contact with gingival connective tissue. In areas of the roots where the periodontal ligament tissue was preserved prior to transplantation, a fibrous reattachment occurred between the root and the adjacent gingival tissue. The results indicate that gingival connective tissue does not possess the ability to establish conditions which enable the formation of a new connective tissue attachment.