• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.28 no.1
• /
• pp.193-204
• /
• 1998

The purpose of this study was to perform the radiographic measurements and temporomandibular joint evaluation in mandibular asymmetry. For this study, thirty-two patients who have mandibular asymmetry were selected and submentovertex, panoramic and lateral corrected tomographic radiographs were taken. Horizontal and vertical analysis using various landmarks on these radiographs were performed. Also radiographic and clinical evaluation of temporomandibular joint were obtained. The results were as follows ; 1. On the submentovertex radiograph, the mean distance of Pogonion to midline was 5.0±3.8mm. 2. The mean distance of Pogonion to Gonion was 100.6±9.2mm in deviated side and 104.3±9.1mm in contra-lateral side, and there was a significant difference between the deviated and the contra-lateral side (p<0.001). 3. The distance difference of Pogonion to Gonion between the deviated and the contra-lateral side was significantly related to the degree of asymmetry (p<0.001). 4. On panoramic radiograph, the condylar height of the contra-lateral side was significantly longer than the one of the deviated side(p<0.001). 5. On lateral corrected tomogram, bony changes of temporomandibular joint were observed in 11 condyles of the deviated side and 9 condyles of the contra-lateral side. Erosion and osteophyte were the most common changes in both the deviated and the contra-lateral sides.

• The korean journal of orthodontics
• /
• v.47 no.1
• /
• pp.50-58
• /
• 2017

Introduction: Identifying menton (Me) on posteroanterior cephalograms and three-dimensional (3D) cone-beam computed tomography (CBCT) images is difficult, because the midpoint of the symphyseal area is not identifiable after the mandibular symphysis fuses at an early age. The aim of this study was to evaluate the reliability of the identification of the genial tubercle (GT) in patients with mandibular asymmetry and to compare it with that of the traditional landmark, Me. Methods: The samples comprised 20 CBCT images of adults with mandibular asymmetry. Two examiners performed the identifications and measurements. Me and GT were marked, and the anteroposterior, vertical, and transverse distances to the three reference planes were measured on 3D-reconstructed CBCT images. The intra- and inter-examiner reliability of landmark identification of Me and GT were assessed using the intraclass correlation coefficient (ICC) and Bland-Altman plots. Results: The Me and GT landmarks showed excellent reliability ($ICC{\geq}0.993$) three-dimensionally. In the transverse evaluation, the ICC values of the GT (range, 0.997-0.999) tended to be slightly higher than those of Me (range, 0.993-0.996). In the Bland-Altman plots for the two separate assessments, Me showed a maximum error of 1.76 mm in the transverse direction, whereas the GT showed a maximum error of 0.96 mm in the 95% limit. Conclusions: Our results suggest that both Me and GT are clinically reliable and equally useful landmarks for the evaluation of mandibular asymmetry on CBCT images.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.41 no.3
• /
• pp.156-164
• /
• 2015

Bilateral sagittal split ramus osteotomy is considered a standard technique in mandibular orthognathic surgeries to reduce unexpected bilateral stress in the temporomandibular joints. Unilateral sagittal split ramus osteotomy (USSO) was recently introduced to correct facial asymmetry caused by asymmetric mandibular prognathism and has shown favorable outcomes. If unilateral surgery could guarantee long-term postoperative stability as well as favorable results, operation time and the incidence of postoperative complications could be reduced compared to those in bilateral surgery. This report highlights three consecutive cases with long-term follow-up in which USSO was used to correct asymmetric mandibular prognathism. Long-term postoperative changes in the condylar contour and ramus and condylar head length were analyzed using routine radiography and computed tomography. In addition, prior USSO studies were reviewed to outline clear criteria for applying this technique. In conclusion, patients showing functional-type asymmetry with predicted unilateral mandibular movement of less than 7 mm can be considered suitable candidates for USSO-based correction of asymmetric mandibular prognathism with or without maxillary arch surgeries.

• The korean journal of orthodontics
• /
• v.52 no.3
• /
• pp.172-181
• /
• 2022

Objective: The objectives of this study were to compare the time-dependent changes in occlusal contact area (OCA) and bite force (BF) of the deviated and non-deviated sides in mandibular prognathic patients with mandibular asymmetry before and after orthognathic surgery and investigate the factors associated with the changes in OCA and BF on each side. Methods: The sample consisted of 67 patients (33 men and 34 women; age range 15-36 years) with facial asymmetry who underwent 2-jaw orthognathic surgery. OCA and BF were taken before presurgical orthodontic treatment, within 1 month before surgery, and 1 month, 3 months, 6 months, 1 year, and 2 years after surgery. OCA and BF were measured using the Dental Prescale System. Results: The OCA and BF decreased gradually before surgery and increased after surgery on both sides. The OCA and BF were significantly greater on the deviated side than on the non-deviated side before surgery, and there was no difference after surgery. According to the linear mixed-effect model, only the changes in the mandibular plane angle had a significant effect on BF (p < 0.05). Conclusions: There was a difference in the amount of the OCA and BF between the deviated and non-deviated sides before surgery. The change in mandibular plane angle affects the change, especially on the non-deviated side, during the observation period.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.35 no.5
• /
• pp.324-328
• /
• 2009

Submentovertex(SMV) projection shows the base of skull, positions of mandibular condyle and zygomatic arches. We would like to investigate how to use SMV and evaluate its availability for the construction of the plan for orthognathic surgery of mandible prognathism and asymmetry. Preoperative Surgical Treatment Objective(STO) using SMV was performed to 12 patients, who visited to Seoul National University Bundang Hospital with chief complaints like mandible prognathism or asymmetry from Dec 2007 to Feb 2009. Surgical splint was made of stone model repositioned according to STO using SMV. We estimate the change in skeletal midline and the stability of occlusion through superposition between preoperative and postoperative SMV. It was effective on the amount of mandible movement and the correction of mandibular asymmetry, while the facial asymmetry involved with maxilla was excluded. It was concluded that STO using SMV is available and predictable method for not only the setback of prognathic mandible but also the correction of mandible asymmetry accurately.

• Imaging Science in Dentistry
• /
• v.43 no.1
• /
• pp.31-36
• /
• 2013

Purpose: This study aimed to measure the bilateral differences of facial lines in spherical coordinates from faces within a normal range of asymmetry utilizing cone-beam computed tomography (CBCT). Materials and Methods: CBCT scans from 22 females with normal symmetric-looking faces (mean age 24 years and 8 months) were selected for the study. The average menton deviation was $1.01{\pm}0.66$ mm. The spherical coordinates, length, and midsagittal and coronal inclination angles of the ramal and mandibular lines were calculated from CBCT. The bilateral differences in the facial lines were determined. Results: All of the study subjects had minimal bilateral differences of facial lines. The normal range of facial asymmetry of the ramal and mandibular lines was obtained in spherical coordinates. Conclusion: The normal range of facial asymmetry in the spherical coordinate system in this study should be useful as a reference for diagnosing facial asymmetry.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.46 no.1
• /
• pp.70-77
• /
• 2020

Osteogenesis imperfecta is a heterogeneous group of connective tissue diseases that is predominantly characterized by bone fragility and skeletal deformity. Two siblings with undiagnosed type I osteogenesis imperfecta underwent orthognathic surgery for the treatment of facial asymmetry and mandibular prognathism. The authors report two cases of combined orthodontics and orthognathic surgery in patients with type I osteogenesis imperfecta, mandibular prognathism, and facial asymmetry.

• Imaging Science in Dentistry
• /
• v.34 no.1
• /
• pp.31-34
• /
• 2004

Purpose: To compare the size of the masseter and lateral pterygoid muscle between the affected and the unaffected side of the patients who have the chief complaints of the mandibular asymmetry. Materials and Methods: Twenty two patients (male: 4, female: 18, average age: 21.3 year-old) were radiographed using posterior-anterior (P-A) cephalography and computed tomography (CT). On P-A cephalography, the degree of deviation was determined by the distance from the mentum to the vertical reference line through the crista galli and the anterior nasal spine. On the scanned tracing papers of the maximum cross-sectional area of the masseter and lateral pterygoid muscle using axial CT images, the pixel number was measured. The ratio of the affected : unaffected sides were obtained. For the masseter and lateral pterygoid muscle, the relationship between the muscular volume and degree of skeletal hypoplasia was studied. Results : The half cases showed no skeletal asymmetry. The lateral pterygoid muscle of the affected side was larger significantly than unaffected side (p<0.05). However, there was no significant difference between two sides in the cases of skeletal asymmetry. There was only significant difference in the cases without skeletal asymmetry (p<0.05). Conclusions : To some extent, the slight mandibular hypoplasia could affect the growth of some masticatory muscles.

• Physical Therapy Korea
• /
• v.26 no.1
• /
• pp.28-36
• /
• 2019

Background: Temporomandibular disorder (TMD) is characterized by pain and limited range of motion in the jaw. TMD patients generally prefer to chew on the unaffected or less-affected side, and this tendency often results in asymmetries in masseter muscle thickness and range of mandibular motion. Objects: The purpose of this study was to compare the asymmetries in masseter muscle thickness and range of mandibular motion in subjects with and without temporomandibular disorders. Methods: Thirty-nine subjects were divided into two groups: A TMD group ($n_1=19$) and a control group ($n_2=20$). The jaw opening range and laterotrusion were measured using a digital vernier caliper. The masseter muscle thickness was examined in both the resting state and the maximal clenching state using ultrasonography. The absolute asymmetry indices calculated based on the laterotrusion and masseter muscle thickness of the respective right and left sides. A two-way ANOVA and a Mann-Whitney U test were used for statistical analysis. Results: No significant different was found in the masseter muscle thickness between the TMD and control group. A significant difference was found in the absolute asymmetry indices of mandibular laterotrusion between the TMD and control groups (p<.05). Furthermore, the ranges of jaw opening were significantly different between males and females (p<.05). The absolute asymmetry index values of masseter muscle thickness at rest and during maximal clenching were also significantly different between males and females (p<.05). Conclusion: These results demonstrated that the subjects with TMD had a larger degree of asymmetry in laterotrusion than those without TMD. Therefore, a physiotherapy program needs to be designed to restore normal laterotrusion capacities for TMD subjects. These results also showed that female subjects had greater absolute asymmetry indices in masseter muscle thickness than male subjects. Therefore, more training is needed to promote bilaterally balanced chewing among women.

• Archives of Plastic Surgery
• /
• v.39 no.4
• /
• pp.281-283
• /
• 2012

The mandibular condyle is a region that plays a key role in the opening and closing of the mouth, and because fracture causes functional and aesthetic problems such as facial asymmetry, it is very important to perform accurate reduction. Traditionally, there has been disagreement on how to manage fracture of the mandibular condyle. This review explores the misunderstanding of mandibular condyle fracture treatment and modern-day treatment strategies.