BONE RESPONSE TO FUNCTIONING IMPLANTS IN DOG MANDIBULAR ALVEOLAR RIDGES AUGMENTED WITH DISTRACTION OSTEOGENESIS

The specific aim of this study was to determine the response of alveol ar bone after it was augmented vertically using distraction osteogenes is and subsequently loaded with implant restorations. Four dogs each h ad four implants placed horizontally into an edentulous mandibular qua drant and, after integration, a distraction osteogenesis device was fa bricated in the laboratory. An osteotomy was made to allow the crest o f the alveolar ridge to be distracted vertically. After 10 mm of verti cal distraction, the device was stabilized with light cured resin. Fol lowing bone fill confirmation of the distraction gap at 10 weeks, two implants were placed into the ridges, one in distracted bone and one i n nondistracted bone. After 4 months for implant integration, freestan ding prostheses were fabricated. Crestal bone levels were evaluated th roughout the period of function. Animals were sacrificed after 1 year of loading, for histologic evaluation of the bone. The vertical ridge augmentation averaged 8.85 +/- 1.05 mm after 10 weeks of healing follo wing distraction, without change over 1 year of implant loading. Histo logic examination showed that bone had formed between the distracted s egments, creating an augmented ridge. The average thickness of the lab ial cortex in the distraction gap was significantly thinner than the l ingual colter in distracted bone and the lingual and labial nondistrac ted cortical bone. The presence of the dental implant did not signific antly affect cortical bone thickness. Serial sections showed that impl ants remained integrated and functional without soft tissue inflammati on. Dental implants placed into alveolar ridges augmented with the tec hnique of distraction osteogenesis maintained bone and were functional for the length of this study.