Periodontal Repair in Dogs: Effect of a Composite Graft Protocol on Healing in Supraalveolar Periodontal Defects

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Abstract
This study evaluated the effect of a composite graft as an adjunct to gingival flap surgery in induced chronic supraalveolar periodontal defects in the mandibular premolar region in beagle dogs. The vertical dimension of the defects, measured from the cemento-enamel junction to the alveolar bone, approximated 5 mm. Root surface treatment in quadrants receiving the graft protocol included conditioning with both critic acid and tetracycline. The composite graft (including: hydroxyapatite, freeze-dried decalcified bone, tetracycline, and fibronectin) was then fitted to the defects. Flaps were placed and sutured to cover most of the crowns of the teeth, but the tips of the cusps. The root surfaces in contralateral jaw quadrants were conditioned with citric acid and the flaps similarly placed and sutured. Dogs were sacrificed 6 weeks after surgery and tissue blocks including teeth and surrounding structures processed for histometric analysis. Connective tissue repair to the root surface in teeth treated with the graft protocol approximated 60% of the defect height. Connective tissue repair in teeth treated with citric acid only was significantly greater and averaged 98% of the defect height (P ≥0.01). Cementum formation was limited following both treatments (approximately 6% of the defect height). Bone regeneration was significantly smaller in grafted sites than in sites treated with citric acid only (approximately 2% and 10% of the defect height, respectively; P ≤0.05). Root resorption was observed in almost all teeth. Ankylosis was present in two citric acid-treated specimens, both from the same dog. Synergistic effects of some or all of the components of the graft protocol may have dictated the healing events in the grafted defects. The composite graft protocol did not offer any advantages over citric acid conditioning of the root surface as an adjunct to gingival flap surgery for periodontal reconstruction in this model system. It is unlikely that the composite graft offers any advantages over any other of its components used alone in regeneration attempts of periodontal defects. J Periodontol 1992; 63:107–113.