Objective: To assess bone volume stability and identify critical bone graft thickness for guided bone regeneration (GBR) simultaneous to implant placement in the maxillary anterior region.
Methods: Eighteen patients were included in the study and received placement of one maxillary anterior implant combined with GBR using deproteinised bovine bone mineral (DBBM) and resorbable collagen membrane. The multilevel buccal bone thickness (BT) was measured by CBCT 1 to 2 weeks and 5 to 8 months post-implantation (at implant uncovering surgery).
Results: Significant buccal alveolar crest collapse (ACCb 1.20 to 1.70 mm) occurred during the mean healing period of 5.3 months (P = 0.000). A greater percentage of ACCb occurred at the coronal aspect of the implant, with 59.24% ± 19.22% at the implant platform and 34.10% ± 30.50% 6.0 mm below the implant platform, respectively. Linear regression analysis demonstrated that if BT was 1.8 to 2.0 mm at the implant platform at uncovering surgery, then it was estimated to have been 4.1 to 4.5 mm immediately post-implantation.
Conclusion: ACCb after maxillary anterior implant placement with simultaneous GBR occurred more coronally than apically. Excessive alveolar ridge augmentation, up to 4.0 mm of hard tissue buccal to the implant platform, should be achieved at the time of surgery to compensate for this potential resorption.