PURPOSE:Few studies have directly compared the quality of bone generated by distraction osteogenesis with that generated by autogenous onlay grafting. The purpose of this study was to compare rates of bone turnover at 5 months in bone produced by distraction osteogenesis and onlay grafting.MATERIALS AND METHODS:Alveolar defects created in jaws of American foxhounds were augmented with distraction osteogenesis or onlay grafting and allowed to heal for 5 months. The animals were then sacrificed and the jaws were resected and prepared for decalcified and undecalcified histologic examination.RESULTS:Both procedures produced bone containing a mixture of haversian systems and trabecular bone. A significantly greater ratio of osteoblast-covered bone surface to total trabecular bone surface (mean +/- SEM) was noted in distraction bone (0.124 +/- 0.049) compared to onlay bone (0.081 +/- 0.048) or control host bone (0.085 +/- 0.042 microm) (P < .05). In addition, significantly (P <.05) greater numbers of osteoclasts per microm of bone surface were noted in distraction bone (0.939 +/- 0.07) compared to onlay bone (0.605 +/- 0.06) or control host bone (0.725 +/- 0.08). No differences in rates of mineralization were noted between the groups.DISCUSSION:While bone from both experimental groups appeared adequate for implant placement, distraction bone appeared to be remodeling at a higher rate than either onlay or control bone.CONCLUSION:Given that the state of healing of the bone in each of these comparative groups was examined at a static point in time, it is premature to draw conclusions about the efficacy of one procedure over the other.

Purpose: The primary goal of this study was to compare bone-to-implant contact (BIC) in alveolar bone augmented by distraction osteogenesis with BIC in alveolar bone augmented by onlay iliac crest grafting. Materials and Methods: Alveolar bone defects were created bilaterally in 5 American foxhounds, and after healing, bone augmentation was accomplished using distraction osteogenesis on 1 side of the jaw and onlay grafting on the other. Twelve weeks after consolidation, implants were placed in augmented and control sites. The animals were sacrificed and the jaws harvested for histologic analysis after an additional 8 weeks. Results: The mean BIC was 54.7% +/- 14.6% for implants placed in distracted sites, 53.8% +/- 11.8% for sites where an onlay graft was used, and 51.2% +/- 14.4% for control sites. Significant differences in BIC were noted between experimental and control sites only at the apical third of the implant (19.8 +/- 1.8 for distracted sites; 15.5 +/- 1.5 for grafted sites; 8.0 +/- 0.5 for control sites; P < .05). Discussion: The data showed that both distraction osteogenesis and onlay grafting produce sufficient bone for implant placement. There were no differences between procedures in regard to BIC after 8 weeks. Conclusion: These data suggest that both onlay grafting and vertical distraction are appropriate methods for bone augmentation prior to implant placement.