Preoperative buccal bone volume predicts long-term graft retention following augmentation in the esthetic zone: A retrospective case series

Objectives Buccal bone augmentation in the esthetic zone is routinely used to achieve optimal clinical outcomes. Nonetheless, long-term data are sparse, and it is unknown how baseline buccal bone volume affects the retention of the augmented volume over time. Material and methods This is a long-term follow-up retrospective case series. After a preoperative computed tomography scan, implants were placed in the anterior maxilla following guided bone regeneration, autogenous block grafting, or both. At the follow-up, patients received a computed tomography scan and a clinical examination. Buccal bone volume was the primary outcome. Buccal bone thickness, peri-implant, and esthetic parameters were secondary outcomes. Results After a median follow-up of 6.7 years (interquartile range: 4.9-9.4), 28 implants in 19 patients (median age at augmentation: 43.3 years, interquartile range: 34.4-56.7, 53% female) were followed up. Preoperative buccal bone volume at baseline (V-0) showed a moderate correlation to final buccal bone volume (V-t, r(s) = .43) but a strong correlation to the absolute volumetric change (Delta V = V-t-V-0, r(s) = -.80). A linear mixed model for V-t had a large intercept of 91.39 (p < .001) and a rather small slope of .11 for V-0 (p = .11). Observed differences between treatments were not statistically significant in the mixed model. V-0 above 105 mm(3) predicted a negative volume change (Delta V < 0) with a specificity of 100% and a sensitivity of 96%. Conclusions The results suggest higher gains in sites with lower V-0 and point to a cutoff V-0 above which the augmented volume is not retained long-term.