A Multi-Center RCT Comparing Titanium-Reinforced dPTFE Membrane to Collagen Membrane in Horizontal Bone Augmentation at Single Sites in the Anterior Maxilla: Clinical and Histological Outcomes

Abstract

Aim: To compare a dPTFE membrane to a collagen membrane in guided bone regeneration (GBR) for horizontal bone augmentation at single sites in the anterior maxilla in terms of alveolar width and bone quality, as clinically and histologically assessed. Materials and Methods: Patients with a class 4 defect (Benic and Hammerle 2014) at a single site in the anterior maxilla (15-25) were recruited in five centers. Following flap elevation and conditioning of the recipient site, they were randomly allocated to the dPTFE membrane group or the collagen membrane group. All patients were treated with a 1:1 mixture of autogenous bone and DBBM. Nine months following bone augmentation, re-entry was performed, intra-surgical clinical measurements were registered, and core biopsies were obtained for histological analyses. Results: Thirty-six patients were randomized (dPTFE membrane group: 8 females, 10 males, mean age 39; collagen membrane group: 14 females, 4 males, mean age 51) and all but one underwent re-entry. GBR was effective in both groups (p < 0.001) yet followed a different pattern over time (p = 0.010) with a higher postoperative alveolar width in the collagen membrane group followed by more graft resorption. At re-entry, the estimated marginal mean alveolar width was 7.0 mm in the dPTFE membrane group and 6.5 mm in the collagen membrane group at re-entry, without statistically significant differences between the groups (p = 0.326). However, infection occurred in 6/18 patients treated with a dPTFE membrane group versus in none treated with a collagen membrane. Clinical assessment at re-entry identified fibrous tissue at the buccal aspect in 7/18 (39%) patients treated with a dPTFE membrane and in 8/17 (47%) patients treated with a collagen membrane, without statistically significant differences between the groups (p = 0.738). Histomorphometric analyses showed newly formed bone in both groups (> 30%) and a minimal amount of DBBM particles (similar to 5%), mostly being in intimate contact with surrounding newly formed bone (similar to 70%). The non-mineralized tissue fraction was 5% higher in the dPTFE membrane group (p = 0.020). There were no significant differences between the groups for other histological outcome measures. Conclusion: Alveolar width enabled implant installation at 9 months in both groups, yet dPTFE membrane was prone to infection. In both groups, fibrous tissue at the buccal aspect was common and newly formed bone was consistently observed.