Block Versus Particulate Deproteinized Bovine Bone Mineral for Guided Bone Regeneration of Peri‐Implant Dehiscence Defects: A 5‐Year Randomized Controlled Trial

To assess the 5-year dimensional stability of buccal hard-tissues following guided bone regeneration (GBR) of peri-implant dehiscence defects using deproteinized bovine bone mineral (DBBM) blocks or particulate. METHODS: Patients requiring single-tooth implants and presenting a buccal dehiscence defect (≥ 3 mm) at implant placement were randomly allocated to GBR using either particulate DBBM or an individually shaped DBBM-block, both covered with a resorbable collagen membrane. Buccal hard-tissue thickness was assessed using cone-beam computed tomography postoperatively, at 6 months and at 5 years. Buccal horizontal thickness at the implant shoulder and corono-buccal thickness measured at 45° were recorded. Secondary outcomes included marginal bone levels, clinical parameters and implant survival. Linear mixed-effects models were used to compare the groups to account for within-subject correlations. RESULTS: Twenty-two of 24 patients completed the 5-year follow-up. Buccal hard-tissue thickness decreased over time in both groups, however, the block-group showed significantly greater dimensional stability. At 5 years, mean buccal horizontal hard-tissue thickness was 1.36 ± 1.16 mm in the block-group and 0.07 ± 0.16 mm in the particulate-group (adjusted mean difference, -1.2 mm; 95% CI, -1.9 to-0.6; p < 0.001). Corono-buccal thickness at 45° was also significantly greater in the block-group (adjusted mean difference, -0.3 mm; 95% CI, -0.5 to -0.1; p = 0.002). Marginal bone levels and clinical parameters showed no clinically relevant differences. No implant loss or peri-implantitis was observed. CONCLUSION: GBR using either DBBM blocks or particulate DBBM resulted in similar peri-implant clinical outcomes and implant survival at 5 years. However, DBBM blocks provided superior long-term preservation of the buccal hard-tissue contour. TRIAL REGISTRATION: Clinical Trial Registration Number, DRKS00005803.