Hard tissue changes after guided bone regeneration of peri‐implant defects comparing block versus particulate bone substitutes: 6‐month results of a randomized controlled clinical trial

Abstract Objectives To test whether block bone substitute used for guided bone regeneration (GBR) of peri‐implant defects leads to different thickness of the augmented hard tissue than particulate bone substitute. Material and methods In 24 patients, 24 two‐piece dental implants were placed >4 months after tooth extraction. Following random allocation, 12 peri‐implant bone dehiscences were grafted with an individually shaped block of deproteinized bovine‐derived bone mineral (DBBM) and 12 bone dehiscences with particulate DBBM. All the sites were covered with a collagen membrane stabilized with resorbable pins. Immediately after wound closure and after 6 months, the horizontal thickness (HT) of the augmented hard tissue was measured at the level of implant shoulder using cone beam‐computed tomography. Results After wound closure, the median HT measured 3.35 mm (mean: 3.38) in the block group and 2.85 mm (mean: 2.73) in the particulate group. At 6 months, the median HT decreased to 2.90 mm (mean: 2.71) in the block group and to 0.2 mm (mean: 0.52) in the particulate group. This difference was statistically significant ( p < .001). Conclusions Block bone substitute used for GBR of peri‐implant defects was superior to particulate bone substitute regarding the dimension of the augmented hard tissue after 6 months of healing.