Vertical Line through the Glabella Point as the Optimized Reference Line of Ideal Maxillary Sagittal Position During Orthognathic Surgery Planning for Chinese Adult Skeletal Malocclusion Patients: A Case-Control Study

Abstract

Objective This study aimed to confirm whether the forehead of skeletal malocclusion patients could be used as a stable reference to guide diagnosis and orthognathic surgery planning. Methods Two parts of case-control study were designed. In first part of the study, three types of skeletal malocclusion patients were included and grouped. The forehead inclination and width were measured and set as the main outcome variables. Multiway ANOVA was performed to detect the statistic difference between skeletal malocclusion types and sex. The component ratio of the patients with the GALL falling directly on the glabella point (Gla) was analyzed. Based on the above results, second part of the study was carried out and the skeletal malocclusion patients who had completed orthodontic and orthognathic treatment were included, which was aimed to verify the values of the vertical line through the Gla as the reference line on diagnosis and guiding orthognathic surgery. Distance between maxillary incisor point and the reference line pre- and post-operation was analyzed as the main outcome variables and using Paired sample t test and one-way ANOVA. Results Two hundred forty-four Chinese patients were included in the first part of the study. Forehead inclination and width values showed significant differences between sexes and part of skeletal malocclusion patients. However, the large inclination and small width result in more than 90% of patients with the GALL falling directly on the Gla with no significant difference. In the second part of the study, the data of 149 patients who had completed treatment showed significant difference between the three types of patients about the distance between maxillary incisor point and the Gla reference line and nonsignificant was found after orthognathic surgery; most of the maxillary incisors fell on the line. Conclusions The vertical line through the Gla could be used as the reference line of ideal maxillary sagittal position for Chinese malocclusion patients.