Crestal bone resorption in augmented bone using mineralized freeze-dried bone allograft or pristine bone during submerged implant healing: a prospective study in humans

Background There is limited evidence on the crestal bone level changes around implants placed in bone augmented by guided bone regeneration (GBR) during submerged healing. The purpose of this study was to prospectively compare radiographic crestal bone changes around implants placed in augmented bone with changes around implants placed in pristine bone. Materials and methods Patients receiving dental implants in the augmented or pristine mandibular posterior edentulous ridge were included in the study. The digital standardized radiographs from the implant placement procedure were compared to the radiographs from the second‐stage procedure to evaluate the peri‐implant marginal bone level changes. The soft tissue thickness (ST), width of keratinized mucosa (wKM), and early cover screw exposure (eIE) were measured at the time of the second‐stage procedure. Results A total of 29 implants in 26 patients, 11 in augmented bone (test group) and 18 in pristine bone (control group), were analyzed. The mean peri‐implant bone loss (ΔBL) was 0.74 ± 0.74 mm (mean ± SD) in the test group and 0.25 ± 0.55 mm (mean ± SD) in the control group. The differences between the test and control groups in the mesial, distal, and mean peri‐implant crestal bone level changes were statistically significant (P = 0.009, P = 0.004, and P = 0.001, respectively). The confounding factors (ST, wKM, and eIE) were adjusted. Conclusions More peri‐implant crestal bone loss during the submerged healing period was observed in augmented bone than in pristine bone. Augmented bone may not exhibit the same characteristics as pristine bone during the implant submerged healing period.