Buccal bone thickness adjacent to virtual dental implants following guided bone regeneration

Crestal bone thickness is a critical determinant of peri-implant tissue stability. This retrospective observational study sought to quantify the buccal bone thickness achieved adjacent to virtual dental implants following guided bone regeneration (GBR) surgery and evaluate the influence of patient- and procedure-related variables on buccal bone thickness.

Cone-beam computed tomography (CBCT) images acquired from patients who had undergone GBR surgery between July 1, 2012, and November 7, 2016, were used for this analysis. In all cases, the GBR procedure involved a dense polytetrafluoroethylene (dPTFE) barrier membrane and a mineralized cortical particulate freeze-dried bone allograft (FDBA). Eighty-four virtual dental implants were placed at planned locations using CBCT images from 84 patients, and the adjacent buccal bone thickness was measured at each site. The effects of sex, age, estimated baseline ridge width, number of missing teeth in site, site type (tooth-bounded versus terminal position in arch), dental arch (mandibular or maxillary), arch location (anterior or posterior), smoking status, titanium reinforcement in the membrane, membrane fixation, and tenting screw use were assessed.

The mean post-GBR buccal bone thickness adjacent to virtual dental implants was 2.24 ± 1.01 mm. Fifty-nine of 84 virtual implants (70%) exhibited buccal bone thickness > 1.9 mm. GBR sites using membrane fixation produced significantly greater virtual implant buccal bone thickness than those without membrane fixation (2.31 ± 0.96 versus 1.15 ± 1.25 mm, P = 0.012). Virtual implant buccal bone thickness also exhibited moderate correlation with estimated initial ridge width (r = 0.43, P < 0.0001). The alveolar ridge at 81 virtual implant sites (96%) was classified as good or satisfactory, meaning dental implants were actually placed at these sites, with or without additional grafting at implant placement.

Observations in this study suggest GBR procedures using dPTFE membranes and FDBA result in favorable ridge dimensions for dental implant placement in most cases. However, additional augmentation at implant surgery may be necessary at ≈ 30% of sites, if buccal bone thickness > 1.9 mm is intended.