Benic GI, et al. - Researchers tested in this investigation whether block bone substitute used for guided bone regeneration (GBR) of peri-implant defects leads to different thicknesses of the augmented hard tissue compared to particulate bone substitute. In 24 subjects, 24 two-piece dental implants were placed >4 months following tooth extraction. After 6 months of healing, block bone substitute used for GBR of peri-implant defects was superior to particulate bone substitute regarding the dimension of the augmented hard tissue.