• The korean journal of orthodontics
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• v.50 no.5
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• pp.324-335
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• 2020

Objective: To compare postoperative positional changes in the mandibular proximal segment between the conventional orthognathic surgery (CS) and the surgery-first approach (SF) using intraoral vertical ramus osteotomy (IVRO) in patients with Class III malocclusion. Methods: Thirty-eight patients with skeletal Class III malocclusion who underwent bimaxillary surgery were divided into two groups according to the use of preoperative orthodontic treatment: CS group (n = 18) and SF group (n = 20). Skeletal changes in both groups were measured using computed tomography before (T0), 2 days after (T1), and 1 year after (T2) the surgery. Three-dimensional (3D) angular changes in the mandibular proximal segment, condylar position, and maxillomandibular landmarks were assessed. Results: The mean amounts of mandibular setback and maxillary posterior impaction were similar in both groups. At T2, the posterior portion of the mandible moved upward in both groups. In the SF group, the anterior portion of the mandible moved upward by a mean distance of 0.9 ± 1.0 mm, which was statistically significant (p < 0.001). There were significant between-group differences in occlusal changes (p < 0.001) as well as in overjet and overbite. However, there were no significant between-group differences in proximal segment variables. Conclusions: Despite postoperative occlusal changes, positional changes in the mandibular proximal segment and the position of the condyles were similar between CS and SF, which suggested that SF using IVRO achieved satisfactory postoperative stability. If active physiotherapy is conducted, the proximal segment can be adapted in the physiological position regardless of the occlusal changes.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.47 no.4
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• pp.249-256
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• 2021

Objectives: The purpose of this study was to evaluate the postoperative anteroposterior stability and improvements in facial asymmetry after performing LeFort I osteotomy in the maxilla, sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) in the mandible, and lateral corticectomy on the IVRO side. Materials and Methods: From July 2009 to October 2018, a retrospective analysis was performed on 11 subjects. Lateral cephalometric radiograph was performed preoperatively (T0), postoperatively (T1), and at 12 months of follow-up (T2), and the B point distance was measured. Posteroanterior cephalometric radiograph was performed preoperatively (S0) and at 12 months of follow-up (S1) and was used to measure five indicators (Ag angle, M-Ag, Co-Ag, Co-Me, and Ag-Me) of facial asymmetry. Results: The B point distances for T0 and T1 were significantly different (P=0.007), whereas those for T1 and T2 were not significantly different (P=0.1). In addition, there was a significant difference between the B point distances of T2 and T0 (P=0.026). Comparison of the facial asymmetry indicators before and after surgery showed a significant difference for all indicators between S0 and S1: the P-values of Ag angle, M-Ag, Co-Ag, Co-Me, and Ag-Me were 0.003, 0.003, 0.008, 0.006, and 0.004, respectively. The Z value was based on negative ranks. Conclusion: There was no significant difference in the B point distances from postoperation to the 12-month follow-up. However, there were significant differences in all five indicators related to facial asymmetry before and after surgery. The values for the five indicators of facial asymmetry all increased postoperatively.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.5
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• pp.559-566
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• 2007

Distraction osteogenesis(DO) is a surgical method of bone formation that involves an osteotomy and sequential stretching of the healing callus by gradual movement and subsequent remodeling. DO is used to correct facial asymmetry, such as in patients with hemifacial microsomia, maxillary or mandibular retrusion, cleft lip and palate, alveolar defects, and craniofacial deficiency. It is accomplished with the aid of a distraction device, which is secured with screws placed directly into bone, for a predetermined length of time. Hemifacial microsomia is characterized by unilateral facial hypoplasia, often with unilateral shortening of the mandible and subsequent malocclusion. Patients with hemifacial microsomia and facial asymmetry have a vertically short maxilla, tilted occlusal plane, and short mandible. Early treatment is necessary to avoid subsequent impaired midfacial growth. The standard treatment of these malformations consists of the application of bone grafts, which can lead to unpredictable growth. The new bone-lengthening procedure represents a limited surgical intervention and opens up a new perspective for treatment, especially in younger children with severe deformities. This report describes a case of hemifacial microsomia(Type-II left-sided hemifacial microsomia). The patient, a 10-year-old child, visited our clinic for facial asymmetry correction. He had a hypoplastic mandible, displaced ear lobe, 10 mm canting on the right side, and malocclusion. We planned DO to lengthen the left mandible in conjunction with a Le Fort I osteotomy for decanting and then perform a right intraoral vertical ramus osteotomy(IVRO). Progressive distraction at a rate of 0.5 mm/12 hours was initiated 7 days postoperatively. The duration of DO was 17 days. The consolidation period was 3 months. Satisfactory results were obtained in our case, indicating that DO can be used successfully for functional, aesthetic reconstruction of the mandible. We report a case involving DO in conjunction with orthognathic surgery for correcting mandibular hypoplasia with a review of the literature.

• The korean journal of orthodontics
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• v.27 no.2
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• pp.283-296
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• 1997

Stomatognathic system is a complex one that is composed of TMJ, neuromuscular system, teeth and connective tissue, and all its components are doing their parts to maintain their physiological relationships. Mandible, in particular, performs various functions such as mastication, speech, and deglutition, the muscular activities that determine such functions are signalled by numerous types of proprioceptors that exist in periodontal membrane, TMJ, and muscles to be controlled by complicated pathways and mechanics of peripheral and central nervous system. Orthodontic treatment, especially when accompanied by orthognathic surgery, brings dramatic changes of stornatognat is system such as intraoral proprioceptors and muscle activities and thus, changes in patterns of mandibular function result The author tried to analyze changes in patterns of mandibular movement and physiologic activities of surrounding muscles in Skeletal Class III ortlrognathic surgery patients who presently show a great increase in numbers. The purpose of this study was to draw some objective guidelines in evaluating funclierual aspects of orthognathic surgery patients. Mandibular functional analysis using Biopak was performed for skeletal Class III prognathic patients who underwent IVRO(lntraoral Vertical Ramus Osteotmy), and the following results were obtained: 1. Resting EMG was greater in pre-surgical group than the control group, and it showed gradual decrease after the surgery. Clenching EMG of masseter and anterior temporalis of pre-surgical group was smaller than those of control group, they also increased post-surgically, and significant difference was found between pre-surgical and post-surgical(6 months) groups. 2. Resting EMG of anterior ternporalis was greater than that of all the other muscles, but there was no significant difference. Clenching EMG of anterior temporalis and masseter were greater than those of the other muscles with statistical difference. In swallowing, digastric muscle showed the highest EMG with statistical significance. 3. Limited range of mandibular movement was shown in pre-surgical group. Significant increase in maximum mouth opening was observed six months post-surgically, and significant increase in protrusive movement was observed three months post-surgically.