Computer simulation of curvilinear mandibular distraction: accuracy and predictability.

Background: The purpose of this study was to retrospectively evaluate the accuracy and reliability of a computer simulation system that predicts the results of an internal curvilinear mandibular distractor in the treatment of hemifacial microsomia and severe mandibular retrognathia.

Methods: A two-dimensional computer analysis and simulation system was developed based on cephalometric radiographs and patient photographs. The software was used to generate and superimpose digital templates, corresponding to the actual distractor and logarithmic spiral, onto the lateral cephalometric tracings. The digital distractor's template was then adjusted to fit the radiographic projection of the actual distractor on the 1-week postoperative lateral cephalograph as precisely as possible. It was then activated along the spiral growth curve template until the ideal position of the mandible was reached. This computational surgical simulation tracing was then superimposed onto the actual postdistraction lateral cephalometric radiograph and tracing. Thus, the predicted and actual mandibular distraction movements were compared.

Results: In all of the cases, the computational distraction (skeletal and soft tissues) tracing fit the actual postdistraction tracing with an accuracy to within 1 mm.

Conclusions: The current study demonstrated that a specific curvilinear distraction can (1) closely reproduce the natural logarithmic spiral movement of the mandibular growth, (2) be closely approximated and thus predicted by a computer simulation system, and (3) be used for correction of mandibular deformities such as hemifacial microsomia and severe mandibular retrognathia.