Method: Three HFM patients treated with DO were recalled at 9 time-points (T1-T9) over 10 years. The skeletal changes in chin position, maxillary width and height, occlusal height, and mandibular length were measured from posteroanterior cephalogram, 45-degree lateral oblique cephalograms, panoramic x-ray and cone-beam CT. Due to differences in traditional 2D radiographs (T1-T7) and 3D images(T8,T9), the ratio between affected and non-affected sides was used to evaluate the degree of asymmetry instead of absolute measurements. The long-term stability was studied for each patient and statistical analyses (a=0.05) were performed.
Result: Clinically significant improvements were seen after DO up to two-year post-DO (T7). Evaluations of the subsequent time-points revealed that with patient’s growth spurt, the growth of the affected side lagged behind the unaffected side, which served as control. Asymmetry was due to inherent growth potential difference rather than surgical relapse of DO. Ten-year post-op (T9) showed that all patients had significant bi-maxillary asymmetry compared to immediate post-op (T2). The degree of asymmetry at T9 was more severe than pre-op time-point (T1).
Conclusion: Even with overcorrection, due to the unpredictable and limited growth potential in affected side, asymmetry worsened in HFM patient over 10-years post-DO. It is recommended early DO to be followed by orthognathic surgery after growth completion.