Primary study of the use of a shape-memory alloy distraction device in the dog mandible for alveolar ridge distraction: determination of osteotomy techniques and evaluation of osteogenesis outcome.

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.