Membrane Fixation and Graft Persistence in Pre-Extraction Buccal Overbuilding: A Split-Mouth Histological Study in Dogs

Background: Buccal overbuilding may support the buccal contour before tooth extraction, but the effect of collagen membrane fixation on graft stability remains unclear. This study evaluated whether pin fixation influences buccal ridge dimensions and graft persistence in a pre-extraction dog model. Methods: In six Beagle dogs, bovine bone mineral was grafted bilaterally at the mandibular first molar region without tooth extraction and covered with a native collagen membrane, fixed with titanium pins at test sites and left unfixed at control sites. After three months, histological measurements were performed. The primary outcome was buccal bone width at 2 mm apical to the cemento-enamel junction. Results: Buccal bone width was 1.02 ± 0.30 mm in the Pin group and 0.89 ± 0.37 mm in the No-pin group. The mean paired difference was 0.13 mm (95% CI: −0.55 to 0.81 mm; p = 0.6875). The combined outer mineralized contour measured 1.06 ± 0.37 mm and 0.95 ± 0.42 mm, respectively. Residual graft occupied 19.4 ± 6.9% of the standardized buccal region in the Pin group and 8.7 ± 6.6% in the No-pin group. Conclusions: Membrane fixation did not significantly improve buccal bone width after three months. The greater residual-graft fraction in the Pin group was exploratory and requires confirmation in studies including tooth extraction and subsequent implant placement.