Comparative stability and outcomes of two surgical approaches for correction of class III asymmetry with lip or occlusal cant.

OBJECTIVES: To assess and compare the stability and outcomes of the two surgical approaches for patients with roll asymmetry. MATERIALS AND METHODS: A total of 50 adult patients were consecutively recruited for this prospective study. Patients with class III asymmetry and lip or occlusal cant who underwent bimaxillary surgery were grouped according to surgical approach: asymmetric posterior impaction on both sides (API, n = 31) and posterior impaction on one side and posterior extrusion on the other side (PIE, n = 19). Postsurgical stability and outcomes between groups were determined with cone-beam computed tomography for facial midline, lip, and occlusal cant at 1 week (T1), and at least 12-month postsurgery (T2, completion of orthodontic treatment). RESULTS: Presurgery, the upper anterior occlusal cant and lip cant were significantly greater for the PIE group (p < 0.05). Postsurgery (T2), the mandible moved upward and rotated upward in both groups. However, the upward rotation was significantly greater in the PIE group compared with the API group. Although the two approaches resulted in significant improvements in facial symmetry, the deviation in the facial midline remained under-corrected for most API patients. CONCLUSIONS: Patient outcomes for mandibular stability and facial symmetry differed between the two surgical approaches for correction of class III asymmetry with lip or occlusal cant. CLINICAL RELEVANCE: The findings of this study suggest that planned over-correction is a reasonable option for the approach of asymmetric posterior impaction on both sides.

Perioral soft tissue change after isolated mandibular surgery for asymmetry patients.

INTRODUCTION: This study was intended to determine whether isolated mandibular surgery for the correction of asymmetry could also change perioral soft tissue asymmetry. PATIENTS AND METHODS: Skeletal class III patients who had undergone mandibular set-back surgery were included. The subjects were composed of two groups with (n = 20) or without (n = 30) menton (Me) deviation over 4 mm. The perioral lip landmarks were analyzed on three-dimensional image from cone-beam computed tomography taken before and 6 months after the operation. The bilateral and inter-group differences and pre- and post-operative changes were statistically analyzed. RESULTS: The corner of mouth on the deviated side was 1.9 mm shorter vertically than that on the contralateral side in patients with asymmetry. After mandibular surgery, the deviated Me moved 5.5 mm to the contralateral side and the lip canting was corrected by 2.4° in the asymmetry group. The degree of Me deviation was significantly correlated with the degree of midline asymmetry in perioral soft tissue landmarks including subnasale, upper and lower lip midline. The predictor variable that affected the changes in lip cant was the surgical correction of Me deviation. DISCUSSION: The correction of chin deviation by isolated mandibular surgery could significantly improve the subnasal and lip asymmetry.

Effect of occlusal plane correction on lip cant in two-jaw orthognathic surgery - A three-dimensional analysis.

INTRODUCTION: The aim of the present study was to evaluate the impact of canting correction in occlusal plane (OP) on the change of lip cant (LC) using three-dimensional (3D) photogrammetry in combination with cone-beam computed tomographic (CBCT) scans in class III asymmetric patients. MATERIALS AND METHODS: Fourteen asymmetric patients with exclusively skeletal class III malocclusion undergoing two-jaw surgery were included. All patients received 3D-photogrammetry and CBCT scans before (T1) and after orthognathic surgery (T2). After image fusion of the CBCT scans, angular correction of the occlusal plane (COP) between T1 and T2 was measured. Accordingly, angular correction of the lip cant (CLC) was analyzed after matching the preoperative 3D-photogrammetric scan to the postoperative. RESULTS: At the T1 stage, the canting of the OP was higher compared to the LC (4.95° vs. 3.77°). During T1 to T2, a significant angular cant correction was observed: COP (2.64°, p = 0.004) and CLC (1.76°, p = 0.01). In addition, a linear relationship between COP and CLC was revealed with a correlation coefficient for angular change of 0.47. For the linear regression COP turned out to be a predictor for CLC (B = 0.372, t (13) = 1.848, p = 0.089). Hence a correction of the OP of 1° resulted in a correction of the LC of only 0.372°. DISCUSSION: The use of CBCT scans in combination with 3D-photogrammetry are valuable tools to accurate analyze canting corrections of the OP and the LC during orthognathic surgery.

Lip line changes in Class III facial asymmetry patients after orthodontic camouflage treatment, one-jaw surgery, and two-jaw surgery: A preliminary study.

OBJECTIVE: To evaluate the effects of orthodontic camouflage treatment (OCT), one-jaw surgery, and two-jaw surgery on the correction of lip line cant (LLC) and to examine factors affecting the correction of LLC in Class III craniofacial asymmetry patients. MATERIALS AND METHODS: A sample of 30 Class III craniofacial asymmetry patients was divided into OCT (n = 10), one-jaw surgery (n = 10), and two-jaw surgery (n = 10) groups such that the pretreatment LLC was similar in each group. Pretreatment and posttreatment cone-beam computed tomography scans were used to measure dental and skeletal parameters and LLC. Pretreatment and posttreatment measurements were compared within groups and between groups. Pearson's correlation tests and multiple regression analyses were performed to investigate factors affecting the amount and rate of LLC correction. RESULTS: The average LLC correction was 1.00° in the one-jaw surgery group, and in the two-jaw surgery group, it was 1.71°. In the OCT group it was -0.04°, which differed statistically significantly from the LLC correction in the other two groups. The amount and rate of LLC correction could be explained by settling of skeletal discrepancies or LLC at pretreatment with goodness of fit percentages of approximately 82% and 41%, respectively. CONCLUSIONS: Orthognathic surgery resulted in significant correction of LLC in Class III craniofacial asymmetry patients, while OCT did not.

The effect of orthognathic surgery on the lip lines while smiling in skeletal class III patients with facial asymmetry.

BACKGROUND: The aim of this study was to examine the relationship between improvements in lip asymmetry at rest and while smiling after orthognathic surgery in patients with skeletal class III malocclusion. METHODS: This study included 21 patients with skeletal class III malocclusion and facial asymmetry. We used preoperative and postoperative CT data and photographs to measure the vertical distance of the lips when smiling. The photographs were calibrated based on these distances and the CT image. We compared preoperative and postoperative results with the t test and correlations between measurements at rest and when smiling by regression analyses. RESULTS: There were significant correlations between the postoperative changes in canting of the mouth corners at rest, canting of the canines, canting of the first molars, the slope of the line connecting the canines, and the slope of the line connecting first molars. The magnitude of the postoperative lip line improvement while smiling was not significantly correlated with changes in the canting and slopes of the canines, molars, and lip lines at rest. CONCLUSIONS: It remains difficult to predict lip line changes while smiling compared with at rest after orthognathic surgery in patients with mandibular prognathism, accompanied by facial asymmetry.

The effect of orthognathic surgery on the lip lines while smiling in skeletal class III patients with facial asymmetry / 대한악안면성형재건외과학회지

BACKGROUND: The aim of this study was to examine the relationship between improvements in lip asymmetry at rest and while smiling after orthognathic surgery in patients with skeletal class III malocclusion. METHODS: This study included 21 patients with skeletal class III malocclusion and facial asymmetry. We used preoperative and postoperative CT data and photographs to measure the vertical distance of the lips when smiling. The photographs were calibrated based on these distances and the CT image. We compared preoperative and postoperative results with the t test and correlations between measurements at rest and when smiling by regression analyses. RESULTS: There were significant correlations between the postoperative changes in canting of the mouth corners at rest, canting of the canines, canting of the first molars, the slope of the line connecting the canines, and the slope of the line connecting first molars. The magnitude of the postoperative lip line improvement while smiling was not significantly correlated with changes in the canting and slopes of the canines, molars, and lip lines at rest. CONCLUSIONS: It remains difficult to predict lip line changes while smiling compared with at rest after orthognathic surgery in patients with mandibular prognathism, accompanied by facial asymmetry.

Change of lip and occlusal cant after simultaneous maxillary and mandibular distraction osteogenesis in hemifacial microsomia.

BACKGROUND: The purpose of this study was to investigate the lip and occlusal cant changes in hemifacial microsomia (HFM) cases after simultaneous maxilla and mandibular distraction osteogenesis (DO) of the mandible. PATIENTS AND METHODS: Retrospective analysis of all HFM cases at Balaji Dental and Craniofacial Hospital were performed. Patient of either gender with all medical imaging records and pre and post-operative (6 months) facial photographs in natural head position were included in the study. The lip cant change was assessed by the angle of each labial commissure and the bi-pupillary reference line. The line joining the frontozygomatic unions and a parallel line is drawn at the level of anterior nasal spine. The occlusal plane is then traced. A vertical line is traced perpendicular to the frontozygomatic union. The deviation of the occlusal plane from the horizontal is measured as the occlusal cant and a change, between pre and post-operative records was considered as the angle and linear measurements. RESULT: With the linear measurement, the mean change in occlusal cant was 7.18 ± 1.47 mm while for the mean change in lip cant was 3.31 ± 0.52 mm (P = 0.120). For the angular measurement, the mean angle change in occlusal cant was 13.86 ± 2.69° and mean change in angle of lip cant was 8.54 ± 0.7° (P = 0.01). DISCUSSION AND CONCLUSION: For type1HFM, DO corrects the occlusal and lip cant. In present study, the lip cant change relative to occlusal cant change was 47.54 ± 10.71% in linear measurements while for angular measurements it was 63.19 ± 10.07% (P = 0.476; Pearson's correlation coefficient = -0.241).