Effect of Membrane Perforations With and Without Collagen Membrane Coverage in Vertical Ridge Augmentation: An Experimental Pilot In Vivo Study

OBJECTIVES: Given the proposed bioactive role of collagen membranes, we aimed to evaluate whether the perforation size of titanium-reinforced dPTFE membranes, with or without an additional collagen membrane, influences outcomes of vertical alveolar ridge augmentation (VARA). MATERIALS AND METHODS: In 12 beagle dogs (24 sites), standardized bilateral chronic mandibular ridge defects (8 × 30 mm) were created and healed for 12 weeks. Sites were randomized (1:1:1) to VARA using porcine xenograft covered with either: (i) non-perforated titanium-reinforced dPTFE (NON-PERF), (ii) perforated titanium-reinforced dPTFE (PERF), or (iii) perforated titanium-reinforced dPTFE covered by a collagen membrane (PERF+CM). After 16 weeks, specimens underwent micro-CT, histology/histomorphometry, vessel quantification, and immunohistochemistry (OCN, ALP, VEGF, TRAP). Continuous outcomes were summarized as medians and compared using the Kruskal-Wallis test with Dunn's post hoc testing when applicable; inflammatory cell scores were analyzed using ordinal logistic regression (α = 0.05). RESULTS: Of 24 treated sites, four had complications and were excluded. All remaining sites achieved around 60% new bone area with no significant intergroup differences (new bone p = 0.5047; soft tissue p = 0.2994; residual graft p = 0.9689). Linear vertical gain was comparable (medians 2.33, 2.87, 2.74 mm; p = 0.7119). Micro-CT outcomes did not differ (e.g., BV/TV, p = 0.2739). Ordinal models did not show significant group differences in inflammatory scores; plasma cell scores in PERF+CM versus control were borderline (OR 15.61; p = 0.0587). CONCLUSIONS: Perforated dPTFE membranes yielded comparable bone gain to unperforated dPTFE. Adding a collagen membrane over perforated dPTFE did not improve VARA outcomes.