[Development of internal distractors for jaws: experimental and clinical studies]

To introduce a series of internal distractors developed by the authors and results of experimental study and clinical trials.

Based on the demand of clinical use and experimental studies, 7 kinds and 17 types of internal distractors were developed. Required biomechanics were evaluated and animal studies were undertaken in 16 Rhesus monkeys and 12 goats with 40 distractors. Clinically, 68 Patients with 7 kinds of severe dento-gratho-facial deformities were treated with 82 distractors and the histocompatibility, stability, influence on new bone formation were evaluated.

The 7 kinds of distractors were State-approved products made of Titanium alloy and permitted for use in human. The pull and twist force tests demonstrated that the loading capability of them were larger than 7.8 kgf and 5.0 kgf respectively. The domestic made Grade II screw was used to transmit the moving, it was nimble, without dead point, and with a forward-backward space of < 0.1 mm. The horizontal space in between the two fixing parts was < 0.1 mm. The parallel degree of the two direction-guide rods was within 0.05 mm. Animal and clinical studies demonstrated that there was no rejection response of the tissues. There were fractures of the direction-guide rods in two early cases, the design was improved then. Other results both experimentally and clinically were satisfactory with good osteogenesis.

This series of domestic made internal distractors can be used satisfactorily in distraction osteogenesis for various kinds of jaw deformities. The successful production of these distractors will provide a good foundation to popularize the internal distraction osteogenesis of the jaws.