Abstract
Background Little evidence is available regarding the benefit of ridge preservation (RP) at molar sites. The primary objective of this three-arm cohort study was to histologically compare the healing outcome between natural healing after molar tooth extraction and two different techniques of RP using freeze-dried bone allograft (FDBA) and a nonresorbable dense polytetrafluoroethylene (dPTFE) membrane, or an absorbable collagen sponge as a barrier. Methods Seventy-nine patients requiring extraction and delayed implant placement were placed into three groups: extraction alone (control); ridge preserved using FDBA; and either dPTFE (Test1) or collagen sponge (Test2). Bone cores were harvested from implant osteotomies at approximate to 3 months after extraction for histomorphometric analysis to determine the percentage of vital bone, residual graft, and connective or other tissue. Ridge dimension changes were also evaluated radiographically (cone-beam computed tomography). Results The percentage of vital bone was significantly greater in control group compared with Test1 but was not statistically different among other groups. Test2 showed significantly less connective or other tissue than control and Test1. The percentage of residual graft was significantly lower in Test1 compared with Test2. There was no significant correlation between the percentage of vital bone or residual graft and the following parameters: healing time, patient age, gender, buccal plate thickness, or radiographic changes in ridge dimensions. Conclusion RP at molar sites using FDBA and an absorbable collagen sponge may be a sufficient and economic way to preserve the ridge dimension without interfering with the amount of new bone formation.