Clinical and radiographic outcomes of allogeneic block grafts for maxillary lateral ridge augmentation: A randomized clinical trial

Background A main drawback of bone block graft surgery is the resorption occurring in early stages of healing. To our knowledge, there are no studies comparing outcomes of freeze-dried bone allograft (FDBA) blocks with different architecture. Purpose The aim of this work was to investigate different factors that can affect graft resorption and to compare the resorption rates of two different types of allogeneic blocks, corticocancellous and cancellous. Materials and Methods A randomized clinical trial was designed. Twenty-eight patients referred for onlay bone augmentation prior to implant placement were included in the study. Preoperative computerized tomography (CT) was taken for all patients. Patients received FDBA blocks of either cancellous or corticocancellous bone obtained from the iliac crest. After a 4-month follow-up, postoperative CT was taken. Then, another surgery was performed, with the purpose to place dental implants. The aforementioned groups were compared for bone resorption and implant outcome using analysis of covariance (ANCOVA) and repeated ANOVA measures, respectively. Demographic data, trabecular bone density, and graft sites were also analyzed. Results A total of 93 implants were placed in the augmented bone sites over 28 patients. A 100% survival rate was achieved during a mean follow-up period of 24 months in both groups. Higher bone resorption rate was found with cancellous bone grafts (29.2% +/- 2.6) compared with corticocancellous grafts (19.3% +/- 2.3). Moreover, higher resorption rates in patients with lower bone density (<185 Hounsfield Units) (31.7% +/- 3.1) and smokers (26.39% +/- 2.3) were observed when compared with patients with higher bone density (>185 Hounsfield Units) (16.8% +/- 2.1) and nonsmokers (22.1% +/- 2.3), respectively. Conclusion Within the limitations of this study, these findings indicate that both corticocancellous and cancellous FDBA grafts constitute a clinical acceptable alternative for bone reconstruction, although cancellous grafts present higher resorption rates. Moreover, host factors such as patient's low bone density and smoking habits may also increase graft resorption rates.