Horizontal ridge augmentation using GBR with a native collagen membrane and 1:1 ratio of particulate xenograft and autologous bone: A 3-year after final loading prospective clinical study

Background Cawood-Howell class IV atrophies, also known as "knife-edge" ridges, represent a serious horizontal defect, making the placement of regular implants challenging. Aim To clinically and radiographically evaluate bone regeneration of severe horizontal bone defects with 3 years of follow-up. Materials and Methods This study was designed as a single cohort, prospective clinical trial. Patients having horizontal bone width of 4 mm or less in the posterior mandible or maxilla were treated with resorbable collagen membranes and a 1:1 mixture of anorganic bovine bone (ABB) and autogenous bone. Implants were inserted and loaded 7 months later. Outcomes were implant and prosthetic survival rates, any biological and prosthetic complications, horizontal and volumetric bone dimensional changes measured on cone beam computer tomography (CBCT), peri-implant marginal bone level (MBL) changes measured on periapical radiographs, plaque index (PI), and bleeding on probing (BOP). Results Eighteen patients received 55 implants. No patient dropped-out. No implant and prosthetic failures and no complications were recorded. Super imposition of pre and 7-month postoperative CBCT scans revealed an average horizontal bone gain of 5.03 +/- 2.15 mm (95% CI: 4.13-5.92 mm). After 3 years, mean MBL was 1.15 +/- 0.28 mm (95% CI 0.84-1.22 mm). The PI was 11.6%, and BOP was 5.2%. Conclusion Within the limitations of the present study, high implant survival rate and high average bone augmentation seem to validate the use of collagen resorbable membranes with a 1:1 mixture of particulate ABB and autogenous bone for the reconstruction of Cawood-Howell class IV alveolar ridge atrophies.