The evaluation of postoperative stability by using conical beam computerized tomography in patients underwent orthognatic surgery due to facial asymmetry

During the growth and development of an individual, maxillofacial structures develop depending on genetic and environmental factors. If the growth of these structures is disproportionate and abnormal, dentofacial deformity may occur. This deformity may be developmental or acquired, or it may occur as a result of trauma, infection and other external factors. Dentofacial anomalies can vary from mild dentoalveolar deformity to severe skeletal disorders that can affect the aesthetic appearance of the face. Facial asymmetry is the size or relationship mismatch between the two sides of the face. Photographs, anteroposterior radiographs, panoramic radiographs, and 3D imaging (CBCT) are used to diagnose facial asymmetry. The aim of this study is to evaluate the long-term stability with measurements to be made on cone-beam computed tomography (CBCT) images taken preoperatively and postoperatively in patients who underwent orthognathic surgery due to facial asymmetry. In this retrospective study, 14 patients with dentofacial deformity who applied to Çukurova University Faculty of Dentistry and who met the study criteria were included. Of the cases, 9 (64.3%) were female and 5 (35.7%) were male. The mean age of the cases was 29.35 ± 3.97 years (21-36 years). During bilateral sagittal split osteotomy (BSSO), posterior bending osteotomy(PBO) method was applied for the treatment of facial asymmetry. CBCT images were obtained from all patients before orthognathic surgery (T0), postoperative 10th day (T1), and 6-12 months postoperatively (T2) (Planmeca Romexis, Helsinki, Finland; 90 Kv; 10 mA; exposure time, 13.5 sec; voxel size, 0.4 mm). To evaluate postoperative stability bigonial distance, Menton (Me) deviation, mandibular cant amount and ramus inclination angle were measured on the CBCT images. To measure these parameters Dolphin Imaging 3D Surgery software (Dolphin Imaging 11.95 premium, Dolphin Imaging & Management Solutions, California, USA) was used. The healing of the gap between the bone segments was evaluated in the axial section. Obtained data were analyzed statistically. When the bigonial distance (mm) measurements were evaluated, no statistically significant difference was found between T0-T1 and T1-T2 periods (p>0.05). On the other hand, the amount of bigonial distance was found to be statistically significantly higher in the T2 period compared to the T0 period (p=0.005). When Me deviation (mm) at T0 period was compared with T1 and T2 periods, a statistically significant difference was found (p<0.001, p<0.001, respectively). On the other hand, there was no statistically significant difference between T1 and T2 periods in terms of Me deviation (p>0.05). No statistically significant difference was found between the periods in mandibular cant (mm) and Ramus inclination angle (degrees) measurements (p>0.05). When the healing of the bone space between the PBO and the proximal segment was evaluated, 85.7% (n=12) of the patients were healed with complete bone tissue, and 14.3% (n=2) with callus tissue. Poor recovery was not detected in any patient. In conclusion, in this study, it was determined that bone interferences were eliminated with PBO performed during BSSO in patients with facial asymmetry, the laterotrusive forces on the proximal segment were minimized, the condyle position was preserved, and as a result, the risk of relapse development was reduced. Keywords: Facial Asymmetry, Orthognathic Surgery, Cone Beam Computed Tomography, Postoperative Stability.