Buccal Bone Wall Thickness Dictates the Extent of Vertical Buccal Bone Loss Following Implant Placement: A Preclinical Study

To assess buccal vertical bone resorption following implant placement in healed sites with varying buccal bone wall thicknesses. In 11 miniature pigs, three tapered hybrid titanium implants were placed per hemi-maxilla in healed bone. Sites were randomised into three groups based on buccal bone wall thickness: G1 (< 1.0 mm), G2 (1.0-1.5 mm) and G3 (> 1.5 mm). Animals were euthanised at 24 h and 2, 4 or 8 weeks. Histological and histometric analyses were performed. The primary outcome was the vertical distance from the transition point (TP) between the machined and moderately rough implant surfaces to the first bone-to-implant contact (fBIC). Healing was uneventful. At 2 weeks, all groups showed buccal resorption, although G3 exhibited earlier bone apposition and fewer resorptive signs. By 8 weeks, all G1 implants displayed exposure of the moderately rough surface, while only one implant in G3 showed exposure. TP-fBIC values at 8 weeks were 0.92 ± 0.63 mm (G1), 0.27 ± 0.54 mm (G2, p = 0.041) and -0.16 ± 0.17 mm (G3, p = 0.0002). Bone-to-implant contact increased over time across all groups. Thin buccal bone walls (< 1 mm) were associated with greater vertical bone loss and implant surface exposure, whereas thick walls (> 1.5 mm) preserved the buccal bone better and protected the implant surface.