Quantitative evaluation of the cheek area after maxillary advancement and rotation by orthognathic surgery in skeletal maxillary retrusion

Aim No quantitative methods for evaluating the cheek line after orthognathic surgery have been reported. The aim of this study was to clarify the effects of orthognathic surgery on the cheek line using computer‐assisted image analysis. Methods This retrospective study involved 101 female participants who underwent orthognathic surgery consisting of both Le Fort I osteotomy and bilateral sagittal split ramus osteotomy. Lateral cephalometric photographs of the patients were analyzed using computer‐assisted image analysis to determine the area surrounded by the cheek line (iCA). The ratio of the postoperative iCA to the preoperative iCA was calculated and denoted as the iCA ratio. Results Participants were categorized into four diagnostic groups according to their malocclusion: Group 1 (maxillary retrusion with mandibular protrusion); Group 2 (maxillary retrusion with mandibular retrusion); Group 3 (maxillary protrusion with mandibular protrusion); and Group 4 (maxillary protrusion with mandibular retrusion). The mean iCA ratio of Group 1 was 1.61, which was the largest value among the four groups. Analyses were performed for Groups 1 and 2 because Groups 3 and 4 had too few cases. When measuring the distances of maxillary forward or backward movement, the iCA ratio was significantly correlated with the distance of maxillary forward movement (correlation coefficients: 0.25 and 0.22 respectively), but not the degree of rotation of maxillary and mandibular movement. Conclusion Maxillary forward movement by Le Fort I osteotomy contributed to the increase of iCA in the profile, which may help to predict the effects of orthognathic surgery on the cheek line.