Histologic analysis of healing after tooth extraction with ridge preservation using mineralized human bone allograft

Background: Ridge preservation was developed as a therapy to prevent severe bone resorption after tooth extraction. The purpose of this study is to determine if there is any difference in the amount of new bone formation ≈3 months after extraction and ridge preservation compared to that after ≈6 months. Methods: Minimally traumatic extraction with ridge preservation using mineralized human bone allograft was performed at 38 single-rooted tooth sites in 33 subjects. Sixteen sites healed for an average of 14 weeks (early healing), whereas 22 sites were allowed to heal for an average of 27 weeks (delayed healing) before harvesting bone core samples. Histomorphometric analysis was performed to determine the percent of new bone formation, residual graft particles, and connective tissue/non-mineralized structures for each site. Results: All specimens showed evidence of new bone formation, with most of the residual graft particles surrounded intimately bywoven bone. No statistically significant differences in the amount of newly formed bone or residual graft particles were found between the two groups. Overall, the early healing group demonstrated amean of45.8%newbone, 14.6%residual graft material, and 39.6% connective tissue/non-mineralized tissue. The delayed healing group showed mean values of 45%, 13.5%, and 41.3%, respectively. Conclusion: The results of this study suggest that waiting ≈6 months after tooth extraction and ridge preservation using mineralized bone allograft does not provide a greater amount of new bone formation or less residual bone particles compared to that after only ≈3 months.