Duong M, et al. - In this investigation, researchers histologically contrasted the healing result between natural healing following molar tooth extraction and two distinct techniques of ridge preservation (RP) using freeze-dried bone allograft (FDBA) and a nonresorbable dense polytetrafluoroethylene (dPTFE) membrane, or an absorbable collagen sponge as a barrier. For this three-arm cohort study, 79 patients were placed into three groups requiring extraction and delayed implant placement: extraction alone (control); ridge preserved using FDBA; and either dPTFE (Test1) or collagen sponge (Test2). According to results, the percentage of vital bone in the control group was significantly higher than in Test1, but not statistically different among other groups. Findings suggested that RP at molar sites using FDBA and an absorbable collagen sponge can be a sufficient and cost-effective way to maintain the ridge dimension without interfering with the amount of new bone formation.