Primary Study of the Use of an Internal, Self-Activated Shape Memory Alloy Distraction Device in the Dog Mandible: Alveolar Ridge Distraction and Implant Placement

Purpose To investigate the use of an internal self-activated distraction device made of titanium-nickel memory alloy to augment the mandibular alveolar ridge. Materials and Methods Twelve adult mongrel canines were randomly divided into 4 groups. Groups I and II were sacrificed 1 month and 3 months after distraction, respectively. In group III (distraction-planting group), 2 implants were placed on both sides of the mandible 3 months after distraction. In group IV (control group), no implants were placed. X-rays were taken and histologic research was performed. Results When the distraction device was in place, the transport segments were lifted up 3.0 to 4.5 mm immediately, and a range of 7.5 to 11.5 mm of augmentation was reached after 3 to 5 days of device activation. X-rays showed that bone mineral density increased, and new bone formed in the distraction area 1 month after distraction. Three months later, the bone mineral density of the distraction area was close to that of the surrounding alveolar bone. Histologic observation showed that collagen bundles initially formed in the distraction region and were followed by calcification and osteogenesis. X-rays showed that the implants were well integrated 3 months after implant placement. The implant-bone interface showed bony integration, and there was no significant difference in the implant-bone contact rate between the distraction and control sides. Conclusion The titanium-nickel memory alloy distractor can be used successfully to augment the posterior mandibular alveolar ridge of canines. New bone formed between the buccal and lingual periosteal layers. A conventional implant surgical procedure could be performed 3 months later and the desirable implant-bone integration was produced.