PURPOSE: The titanium-nickel shape-memory alloy distractor is a new kind of alveolar ridge distraction device that can be completely buried and self-activated. To evaluate this new device, the present study compared the effects of 2 osteotomy techniques and investigated the osteogenesis outcome by measuring the bone mineral density and biomechanical properties of newly generated bone tissues. MATERIALS AND METHODS: Adult mongrel canines (n = 18) were randomly divided into 3 groups. All the mandibular teeth were extracted. Group I received a complete osteotomy, whereas groups II and III received a partial osteotomy with preservation of the glossal cortical bones. The left mandible served as the experimental site for each group, and the right side served as the internal control. Groups I and II were sacrificed 3 months after the completion of distraction, whereas group III was sacrificed 6 months after the completion of distraction. Radiographs were taken. Dual-energy x-ray absorptiometric results and compressive biomechanics of the distracted and control bone masses were examined for groups II and III (partial osteotomy group). RESULTS: The complete osteotomy group exhibited a larger distraction space initially; however, the distracted area showed a remarkable depression on the buccal-glossal side. In contrast, the partial osteotomy groups exhibited a nearly normal mandibular morphology. The bone mineral density, compressive strength, and elastic modulus were decreased in the distracted side compared with the control side 3 months after distraction. These 3 parameters increased in the distracted side 6 months after distraction, which did not differ significantly from those in the control side. CONCLUSIONS: Partial osteotomy with preservation of the glossal cortical bones is more suitable for alveolar ridge augmentation using the shape-memory alloy distraction device. The newly generated bone exhibited adequate strength, which can satisfy the requirements of subsequent implantation.
[Show abstract][Hide abstract] ABSTRACT: IMPORTANCE Although a number of mandibular and occlusal problems may be addressed by orthodontic treatment alone, dentofacial osteotomies are often needed to achieve desired functional or cosmetic results. With the increased popularity of mandibular distraction osteogenesis in recent years, the role of the facial plastic and reconstructive surgeon is crucial in the multidisciplinary care of patients with such problems. OBJECTIVE To review the history and evolution of mandibular osteotomies and distraction osteogenesis and to discuss indications, advantages, disadvantages, and recent advances of these techniques. EVIDENCE REVIEW MEDLINE and PubMed searches without date limits, confined to publications in English, German, and French languages were used to search for terms mandibular advancement, mandibular osteotomy, orthognathic surgery, mandibular distraction osteogenesis, prognathism, and retrognathism in the respective languages. References not found on the sources noted were found in print form in the New York Medical College Library when needed. Particular techniques, as originally described or relating to mandibular osteotomies and mandibular distraction osteogenesis, were critically reviewed. FINDINGS The goal of surgical mandibular modification procedures is to correct a variety of craniofacial abnormalities for both functional and aesthetic purposes. Multiple techniques of both mandibular osteotomy and distraction osteogenesis have been shown to be effective. Their effectiveness and utility is primarily determined by the specific craniofacial defect and desired outcome, as well as surgeon preference and patient compliance. CONCLUSIONS While mandibular osteotomy has evolved tremendously, distraction osteogenesis continues to grow as a leading method of surgical correction for a variety of craniofacial defects. Current research shows significant strides in making distraction more effective and efficient to use for both the surgeon and the patient. With the growing popularity of these procedures, the up-to-date knowledge of the facial plastic and reconstructive surgeon in these advances is of utmost importance.
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