Advantage of three-dimensional models in intraoral callus distraction.

Distraction osteogenesis has become an important method of reconstructing hypoplastic facial bones. Intraoral callus distraction is a great aesthetic improvement, because no visible scars are caused. Precise preoperative planning is necessary, however, because the direction of distraction cannot be influenced postoperatively. Nine three-dimensional (3-D) models were used in three intraoral distraction cases: two patients suffered from unilateral hemifacial microsomia and one from micrognathia after bilateral ankylosis caused by multifocal osteomyelitis in childhood. In each case, models of the head were produced and the distraction was simulated preoperatively. The amount of distraction was 18 mm in the two hemifacial microsomia patients and 18 and 14 mm in the ankylosis case. Extension of distraction in the ankylosis patient was shorter on one side in order to achieve a correct midline position. A slight overcorrection of 3-5 mm was allowed to cover relapse and unpredictable future growth deficiency. Three-dimensional models can supply important information when employed in intraoral callus distraction. They allow anticipation of pitfalls and help to achieve a foreseeable result. Further advantages may be expected with complete 3-D enoral distraction in the future.