Methods: Fourteen patients (mean age: 52) who were in need of dental implants at areas with osseous defects in the mandible were selected. In the test group (n=7), alveolar cortical bone at the area of regeneration was perforated using a #2 high speed round bur. No decortication of cortical bone was performed in the control group (n=7). Subsequently, defects were augmented by guided bone regeneration using resorbable membrane and bovine bone. After a healing period of 7 months, implant sites were created and trephine cores harvested for histological and histomorphometric analysis of the grafted areas.