PurposeThe aim of the present study was the histomorphometric and cephalometric comparison of autogenous bone grafting of the anterior iliac crest and the application of bovine bone substitute concerning new bone formation and postoperative stability in patients undergoing orthognathic Le Fort I osteotomy. Patients and methodsTwenty-five patients requiring orthognathic surgery with Le Fort I osteotomy were included in this study. Patients were randomly divided into three groups receiving either autogenous iliac crest BONE grafting (BONE; n = 8) or xenogenic bovine bone grafting (Bio-Oss®) in INTER (n = 12) or in ONLAY (n = 5) position. Histomorphometric analysis was performed using trephine bone biopsies from the autogenous, respectively xenogenic bone grafting region. Postoperative stability was evaluated using teleradiographies of three different timepoints. ResultsAll groups showed comparable mineralized fractions in bone biopsies of 50.2% (±13.2%) INTER, 46.48% (±12.3%) ONLAY and 57.1% (±20.6%) BONE as well as comparable percentage of connective tissue. Patients in the INTER-group revealed the lowest relapse rate of 20.5% (INTER) compared to 30.3% (ONLAY) and 33.0% (BONE). All groups underwent comparable maxillary advancement and healing time. ConclusionsPresent results indicate that block shaped bovine bone substitute is a promising alternative to autogenous bone grafting to bridge the Le Fort I osteotomy gap in orthognathic surgery.