A randomized controlled trial on the impact of healing time on wound healing following ridge preservation using a 70%/30% combination of mineralized and demineralized freeze-dried bone allograft

Background: To compare the histologic difference in healing between ridge preservation sites treated with a combination allograft of 70% mineralized and 30% demineralized freeze-dried bone allograft (FDBA) evaluated at 8 to 10 weeks versus 18 to 20 weeks post-extraction. Changes in morphological ridge dimensions were also evaluated. Methods: Forty-four patients with a single-rooted tooth to be extracted and replaced by a dental implant were recruited for this study. At time of extraction, measurements were taken with a custom acrylic stent, and the extraction socket was grafted with the combination allograft and covered with a nonresorbable membrane. Patients were randomly assigned to the short-term (8 to 10 weeks) or long-term (18 to 20 weeks) healing group. Sites were re-entered for study measurements, a bone core sample, and implant placement. Bone cores obtained during implant placement were analyzed histologically to determine percentages of vital bone, residual graft, and CT/other. Results: Thirty-eight of the 44 patients completed the study, 19 in each group. There was a significant difference between the two groups for mean percent vital bone formation (short-term = 18.17%, long-term = 40.32%, P = < 0.0001) and percentage of residual graft (short-term = 41.54%, long-term = 23.59%, P = < 0.0001). There was no difference in morphological changes between the two groups. Conclusion: Ridge preservation using combination FDBA resulted in approximately twice as much vital bone and half as much residual graft material after 18 to 20 weeks of healing compared to only 8 to 10 weeks healing.