Vertical alveolar bone distraction at molar region using lag screw principle.

PURPOSE: Recently, alveolar bone distraction has been widely used and several devices have been developed for this purpose. However, there are some disadvantages in each device, especially for distraction of posterior alveolar ridge. The purpose of this study was to develop a new device for vertical alveolar bone distraction at the molar region and to show the results of its clinical application.

MATERIALS AND METHODS: The mechanism of device is based on lag screw principle and the device consists of the following 4 components; distraction screw, hole implant fixture, supporting plate, and temporary short implant and/or neighboring natural teeth. The distraction screw suspended at the supporting plate is inserted into the internal thread of the hole implant fixture placed at alveolar transport segment. If the distraction screw turns at the supporting plate, the hole implant fixture with transport segment moves to the supporting plate without vertical movement of the screw at the supporting plate like a lag screw. After an animal experiment using 4 beagle dogs, the device was clinically applied in 4 patients before implant insertion.

RESULTS: The distraction of the alveolar bone could be successfully performed in all patients without any complications. The direction of distraction with this device could be adjustable, and the alveolar bone could be distracted not only vertically but also horizontally. Moreover, the surgical technique is simple with no need for a second surgery, and there is no occlusal disturbance from the device.

CONCLUSIONS: The new device for alveolar bone distraction using lag screw principle can be used effectively in the molar region.