OBJECTIVETo study the possibility of mandibular alveolar ridge augmentation by distraction osteogenesis using TiNi-SMA (shape memory alloy) distractor.

METHODSAll of the mandibular premolars and the first molar were extracted from ten adult mongrel canines. One month later, box-shaped osteotomies of the alveolar bone were performed out and TiNi-SMA distractors were buried in experimental group. The bone height was measured before and 1, 5, 13 weeks after the operation. The radiographs were taken on the day of, and 1, 5, 13 weeks after operation. The animals were killed at one or three months after distraction and examined histologically.

RESULTSThe bone segments were lifted up immediately after the insertion of distractors and the height achieved 7.5 - 11.5 mm one week after the operation. One month after distraction, the radiographs showed there was regeneration of bone in distraction gap. The new bone and the normal bone could not be differentiated clearly three months after distraction. No bone resorption was found during this period. In histological sections, there were collagen bundles in early distraction, then these bundles were calcified and became traeculaes.

CONCLUSIONIt suggests that the canine mandibular posterior alveolar ridge can be augmented by distraction osteogenesis using TiNi-SMA distractor, and the new bone is formed by intramembranous ossification.