3D Assessment of Asymmetry Prior to Treatment of Hemifacial Microsomia

Objectives: To evaluate the asymmetry location in hemifacial microsomia, assessing diagnostic deviations in right and left size, shape and position of all surfaces of the mandibular condyles, rami and body. Methods: 3D Cone-beam CT (CBCT) scans were taken at pre-treatment for 10 subjects with hemifacial microsomia. To compare right and left side differences, the CBCT image was mirrored on an arbitrary plane then registered on the cranial base to the original patient image. The average surface distances of the right and left sides were calculated for different regions of the mandible. Results: The 3D models showed the condylar position was 6.5mm more lateral in the side of costo-condral graft for 1 case. For all cases, the affected side of the mandible showed a vertically shorter mandibular ramus, with surface distances varying between 3.25 to 9.86 mm when the mirror images were superimposed to the actual patient image. The lack of lateral growth of the mandibular rami on the affected side varied from 2.47 to 6.54 mm for the ten cases assessed. The 3D display of asymmetry revealed variability its location and measures. Conclusion: Preliminary data on 3D modeling of asymmetry in patients with hemifacial microsomia indicates that quantification and location of asymmetry may aid precise surgical planning, as this information is not obtained from conventional 2D methods and clinical assessment. Diagnostic 3D imaging of asymmetry has the potential to decrease the need for surgical exploration (Supported by NIDCR DE005215-26).