Deproteinized bovine bone remodeling pattern in alveolar socket: a clinical immunohistological evaluation.

OBJECTIVES: Considering the low rate of deproteinized bovine bone (DBB) graft resorption in vivo and vitro, the aim of this study was to investigate, through an immunohistochemical method, DBB remodeling patterns in human.

MATERIAL AND METHODS: Socket preservation, a highly documented and affirmed technique, was selected as the best in vitro model to analyze DBB effect on bone remodeling. Following premolar extraction (T0), 20 patients were randomized into two treatment groups. In the test group (t), the alveolar sockets were grafted with DBB, while in the control group (c) no bone graft was applied and the alveolar sockets were left to heal spontaneously. After 5 months, a re-entry procedure was performed, and one implant was placed according to manufacturer's protocols (T1). Bone biopsies were harvested for each patient both at T0 and at T1. On the bone samples, immunohistochemical investigations were performed to analyze BMP-2, BMP-7, ALP, IL-6, TNF-α expression.

RESULTS: Bone morphogenetic proteins were more expressed in the control group than in the test group (BMP-2: P < 0.001; BMP-7: P = 0.017), while TNF-α value was larger in the test group (P < 0.001); no statistically significant differences were observed for the other markers. When considering time as the main variable, statistically significant differences were found for BMP-2 (P < 0.001), BMP-7 (P < 0.001), IL-6 (P < 0.001), ALP (P < 0.05), and TNF-α (P < 0.001). Significant interaction between groups and time was found for BMP-2 (P < 0.001), BMP-7 (P < 0.001), TNF-α (P < 0.001).

CONCLUSIONS: Deproteinized bovine bone guarantees the activity of bone remodeling processes in human extraction socket at 5 months of healing, bringing to a higher expression of anabolic and catabolic bone markers.