Effect of Citric Acid and Various Concentrations of Fibronectin on Healing Following Periodontal Flap Surgery in Dogs

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Abstract
The purpose of this histologic and histometric study was to examine the effect of citric acid and increasing concentrations of fibronectin on new connective tissue attachment following periodontal flap surgery. Full thickness, mucoperiosteal flaps were elevated in six healthy mongrel dogs. Two to 3 mm of alveolar bone were removed along the buccal aspect of the teeth in the mandible and into the interproximal areas of each surgical site. Cementum was removed from the exposed root surfaces and reference notches were inscribed into the roots at the margin of the recontoured bone. Citric acid, pH 1.0, was applied to the instrumented root surfaces for 3 minutes and rinsed with sterile saline. Both the root surfaces and the inner surface of the flap were then bathed in either sterile saline or increasing concentrations (0.38, 0.75 and 1.5 mg/ml saline) or exogenous fibronectin. All the flaps were returned to their original preoperative positions, secured using figure 8 sutures with 4– 0 braided silk and allowed to heal. Two dogs per time‐point were sacrificed at 1, 2 and 6 weeks after surgery. Block specimens of the surgical sites were demineralized and serial sections prepared for histologic and histometric evaluations. Histologically, tissue sections were examined for: (1) epithelial proliferation and attachment, (2) periodontal fiber organization and maturation, (3) inflammatory cell types, (4) presence or absence of new cementum deposition and (5) degree of vascularity of the tissues. Histometric measurements were taken: (1) from the root surface notch to the apical extent of the junctional epithelium and (2) from the apical extent of the junctional epithelium to the free gingival margin. The four treatment modalities were compared by the use of repeated measurement analysis of variance. When significant differences were found, the Newman‐Keuls procedure was used to make individual comparisons between each pair of mean values. Results of the study demonstrated a significant increase in new connective tissue attachment in all surgical sites where exogenous fibronectin had been added, but there was no obvious advantage in increasing the concentration of fibronectin above the plasma level (0.38 mg/ml).