GUIDED TISSUE REGENERATION COMBINED WITH OSSEOUS GRAFTING IN SUPRABONY PERIODONTAL LESIONS - AN EXPERIMENTAL-STUDY IN THE DOG

The purpose of the present investigation was to evaluate the use of bone grafts in combination with the GTR-procedure in reinstituting periodontal support around teeth with horizontal bone loss. Orthodontic elastic bands were placed around mandibular and maxillary premolars in 3 dogs in order to induce breakdown of the periodontal tissues. When the destruction had reached a level corresponding to approximately half the root length, the elastic bands were removed and the teeth were scaled. After a period with plaque control, mucoperiosteal flaps were elevated on the buccal and lingual aspects of the experimental teeth. The exposed root surfaces were curetted, and a notch was made at the level of the reduced bone crest. In randomly selected test quadrants, Kielbone(R) mixed with fibrin sealant (Tisseel(R) was placed in the interproximal space and in the bifurcations. Both the buccal and lingual aspect of the test teeth were then covered by a teflon membrane (Zitex(R)) and the raised tissue flaps sutured in a coronally displaced position. The contralateral teeth (controls) were treated the same way, except that fibrin sealant without Kielbone was applied in the bifurcations and the interproximal space prior to the placement of the membranes. The membranes were removed by a 2nd operation after 35 days. Clinically, various complications were observed during healing. The buccal and lingual flap margins consistently failed to join in the interproximal area, and increasing recession of the flap margins and exposure of the membranes, resulting in accumulation of bacterial deposits and food debris, occurred during the period the membranes were maintained. The histological analysis after 3-4 months of healing failed to demonstrate any consistency in periodontal regeneration in both test and control specimens, and no appreciable differences were observed between the 2 groups. On 10% of the bifurcation surfaces in the test teeth and on 18% of those in the controls, the gain of attachment exceeded 2 mm. The treatment had mainly resulted in bone loss but also regrowth of bone had occurred. The results suggest that the application of the large membranes have resulted in poor wound closure, thereby facilitating contamination of the treated area, which may have disturbed healing and led to exfoliation of the grafted materials.