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Background: Natural head position (NHP), pharyngeal airway and maxillofacial growth pattern are correlated. The author's previous studies proved that following surgical correction of Skeletal Class II malocclusion, the over‐extended NHP returned upright, and the pharyngeal airway space (PAS) dimension expanded. Objective: The present study compares the post‐operative change in NHP and PAS after orthognathic surgery in Skeletal Class II and III malocclusion patients. Methods: Patients receiving orthognathic procedures to correct Skeletal Class II or III malocclusions were reviewed in this retrospective study. Pre‐operative and 6‐week post‐operative cone‐beam computed tomography datasets were collected. Variables representing the craniofacial pattern, the NHP and the PAS were measured three‐dimensionally. Post‐operative variables were compared with their pre‐operative counterparts using either repeat‐measure 2‐way analysis of variance or Wilcoxon matched‐pairs signed rank test. Results: Thirty cases of Skeletal Class II malocclusion and 13 cases of Skeletal Class III malocclusion were collected. Preoperatively, the inter‐group differences were significant in craniofacial pattern (68.14 ± 3.552 degree vs. 79.63 ± 2.497 degree, p <.0001) and the NHP (68.77 ± 11.02 degree vs. 82.83 ± 7.738 degree, p =.0002) while not significant in PAS; after surgery, the intergroup differences in craniofacial pattern and the NHP between groups decreased, and the PAS increased in both groups. Conclusion: Orthognathic surgery may improve compromised NHP and increase PAS in Skeletal Class II and III malocclusion patients. [ABSTRACT FROM AUTHOR]

We investigated the change in the natural head position and its relation to the change in the mandibular position in patients with mandibular hypoplasia. Forty-one patients treated by orthognathic surgery were divided into three groups: bilateral sagittal split osteotomy (BSSO) advancement (n = 8); BSSO advancement with genioplasty (n = 12), and Le Fort I osteotomy with BSSO advancement (n = 21). Cone-beam computed tomographic (CT) datasets were collected preoperatively and six weeks postoperatively. The natural head position was measured using the craniocervical angle and the distance from the second vertebra to the frontal plane, and the mandibular position was measured using the craniomandibular angle and the distance from the mandible to the frontal plane. Repeated measures two way ANOVA was used to assess the significance of differences between the angular and linear measurements, and Pearson’s correlation coefficient to assess those between the change in the mandibular position and the natural head position. The craniomandibular angle increased and the mandible to frontal plane distance decreased, as planned; the craniocervical angle increased, and the distance from the second vertebra to the frontal plane decreased in all three groups. ANOVA showed a significant difference in the time factor (preoperative compared with postoperative) but no significant differences between the groups or interaction (time multiplied by group) factors. There was a significant correlation between the change in mandibular position and the change in the natural head position. Changes in the natural head position after correction of mandibular hypoplasia are correlated with the change in the mandibular position, regardless of whether a genioplasty or Le Fort I osteotomy was done. [ABSTRACT FROM AUTHOR]

Our aim was to assess the accuracy of computer-aided orthognathic surgery for maxillary repositioning in 15 patients with mandibular hyperplasia and normal temporomandibular joints (TMJ). We aligned preoperative and postoperative virtual skulls at the cranium using surface superimposition then recorded and calibrated three 3-dimensional coordinates (maxillary dental landmarks U0, 6R, and 6L) on the skulls. Errors between these preoperative and postoperative landmarks were calculated and the largest error of every patient was chosen for assessment. Landmark errors ranged from 1.00 – 2.49 mm, and recording errors from −0.06 – 0.07 mm. The superimposition error was mean (SD) 0.036 (0.002) mm. The accuracy of the method is acceptable in patients with a normal TMJ. [ABSTRACT FROM AUTHOR]