Evaluation of virtual surgical plan applicability in 3D simulation-guided two-jaw surgery

Three-dimensional (3D) simulation-based orthognathic surgery is becoming a more popular technique. Therefore, standardized methods for evaluating the efficacy and reliability are required. The virtual surgical plan (VSP) applicability, which represents the degree of similarity between planned movements and actual surgical events, should be accurately measured as a separate entity. We present our method of calculating the VSP applicability and investigating the effect of some factors that are suspected to affect this applicability.

This retrospective study included 35 patients who underwent simulation-guided two-jaw surgery. The absolute differences between actual (Ta) and planned (Tp) travel distance of selected points were used as the absolute misapplication index (abMAI), whereas the ratio of this difference to the overall distance represented the relative form (rMAI).

Mean abMAI was 1.11 mm [standard deviation (SD), 1.13] with significant differences (p < 0.001) between the maxilla (mean, 0.82; SD, 0.6 mm) and mandible (mean, 1.7; SD, 1.5). Using rMAI, calculated by ((Ta-Tp)²Ta), we found no significant difference between the mandible and maxilla (p = 0.186). The correlation test of distance revealed no significant correlation with rMAI. Analysis of the factors affecting the applicability showed that the cleft-related deformities were associated with lower applicability than noncleft-related deformities (p = 0.006).

Thus, rMAI can be used to measure the VSP applicability regardless of the magnitude of the travel distance. Among all the factors studied, cleft-related deformities were found to be associated with lower applicability.