• The korean journal of orthodontics
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• v.53 no.3
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• pp.185-193
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• 2023

Objective: The growth and development of the mandible strongly depend on modeling changes occurring at its ramus. Here, we investigated covariance patterns between the morphology of the ramus and the rest of the face. Methods: Lateral cephalograms of 159 adults (55 males and 104 females) with no history of orthodontic treatment were collected. Geometric morphometrics with sliding semi-landmarks was used. The covariance between the ramus and face was investigated using a two-block partial least squares analysis (PLS). Sexual dimorphism and allometry were also assessed. Results: Differences in the divergence of the face and anteroposterior relationship of the jaws accounted for 24.1% and 21.6% of shape variation in the sample, respectively. Shape variation was greater in the sagittal plane for males than for females (30.7% vs. 17.4%), whereas variation in the vertical plane was similar for both sexes (23.7% for males and 25.4% for females). Size-related allometric differences between the sexes accounted for the shape variation to a maximum of 6% regarding the face. Regarding the covariation between the shapes of the ramus and the rest of the face, wider and shorter rami were associated with a decreased lower anterior facial height as well as a prognathic mandible and maxilla (PLS 1, 45.5% of the covariance). Additionally, a more posteriorly inclined ramus in the lower region was correlated with a Class II pattern and flat mandibular plane. Conclusions: The width, height, and inclination of the ramus were correlated with facial shape changes in the vertical and sagittal planes.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.1
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• pp.26-34
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• 2003

Intraoral Vertical Ramus Osteotomy,along with Sagittal Split Ramus Osteotomy,is an popular surgical technique performed on mandibular prognathism. However Intraoral Vertical Ramus Osteotomy has been suspected for an initial mobilization at the healing phase of segment because it does not employ the rigid fixation between segments. To execute a study on the healing phase of segment after Intraoral Vertical Ramus Osteotomy on the horizontal plane, 102 patients (204 parts) who were diagnosed mandibular prognathism and took Intraoral Vertical Ramus Osteotomy at the Yonsei University dental hospital were observed during the period of before operation, immediately postoperation, 1 month, 3 months, 6 months, and 12 months. The change in the width of segment and horizontal angle of proximal segment and condylar head on the Submentovertex Cephalogram taken from those patients represented following results. 1. The width of proximal and distal segment decreased with the lapse of time. It decreased into 84.5% between immediate postoperative and 6M and even continued to decrease till 12M. 2. The horizontal angle of the proximal segment did medial rotation according as the lapse of time and rigorously continued till 3M. The rotation angle of condylar head indicated its tendency of recurrence to the original position but the entire recurrence was not allowed. The bigger an initial angle was, the higher was the tendency of recurrence after the operation while the rotation angle remained still bigger. 3. After grouping into group 1, group 2,and group 3 based on the extent of the variation of rotation angle of condylar head at immediate postoperative, the variation of rotation angle was measures in each group. The result presented that the initial rotation angle of condylar head had correlation with that of proximal segment but had no relation with the extent of setback of the mandible. However a quantitative analysis alone is not a sufficient method for analyzing the healing phase of segment on the horizontal plane.Therefore a multilateral analysis using 3 dimensional data such as CT is recommendable for the future study.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.3
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• pp.193-203
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• 2001

Orthognathic surgery of the mandibular prognathism and the retrognathism is tend to be performed on the mandibular ramus to prevent inferor alveolar nerve injuries. The purpose of this study is to find a safe and accurate reference point on mandibular ramus for orthognathic surgery by comparative anatomical study of dentofacial deformity patients. We use 38 Korean Cadavers with normal occlusion(Group 1), 3-dimensional simulation of computerized tomogram of 23 patients with retrognathism (Group 2), 27 patients with mandibular prognathism (Group 3). Following results are obtained : 1. The maximum thickness of the mandibular ramus is $8.78{\pm}1.15mm$ for Group 2, $7.61{\pm}1.26mm$ for Group 1, $6.95{\pm}0.82mm$ for Group3 respectively (P=0001). The minimum thickness is $5.51{\pm}1.08mm$ for Group 1, $5.06{\pm}0.40mm$ for Group 2, $4.56{\pm}0.78mm$ for Group3, respectively (p=0.0001). But, the thickness at the level of 5mm above the lingular is $0.78{\pm}0.65mm$ for Group 2, $5.63{\pm}1.28mm$ for Group 1, $5.32{\pm}0.91mm$ for Group 3, respectively. There is no significant difference between these groups(P=0.0510). 2. The horizontal location from the midwaist point to lingular is $0.18{\pm}1.57mm$ for Group 1, $0.69{\pm}1.33mm$ for Group 2, $0.66{\pm}1.66mm$ for Group 3, and there is no significant difference between these groups(p=0.0835). But the vertical location from the midwaist point to lingular is $1.45{\pm}2.64mm$ for Group 1, $0.63{\pm}1.44mm$ for Group 2, $0.34{\pm}1.81mm$ for Group 3, and there is significant difference between these groups(p=0.0030). 3. The horizontal location from the midwaist point to mandibular foramen is $0.29{\pm}1.75mm$ for Group 1, $0.63{\pm}1.44mm$ for Group 2, $0.34{\pm}1.81mm$ for Group 3, and there is no significant difference between these groups(p=0.5403). But the vertical location from the midwaist point to mandibular foramen is $-3.33{\pm}4.43mm$ for Group1, $-4.79{\pm}2.26mm$ for Group 2, $-6.06{\pm}2.99mm$ for Group 3, and there is significant difference between these groups(P=0.0001). 4. The horizontal length from the disto-buccal cusp tip of mandibular second molar to lingula is $30.97{\pm}4.17mm$ for Group 3, $28.29{\pm}2.65mm$ for Group 1, $25.48{\pm}0.77mm$ for Group 2 (p=0.0000), and also vertical length is $7.72{\pm}3.22mm$ for Group 3, $6.38{\pm}1.83mm$ for Group 1, $5.89{\pm}2.30mm$ for Group 2 (P=0.0014). 5. The location of lingular is 0.50 from anterior border of mandibular ramus in all groups, if it assumed the length from anterior border to posterior border is 1. And it is almost 0.33 from the sigmoid notch, if it assumed the length from sigmoid notch to antegonial notch is 1. 6. In Group 1, Antilingular prominence is located on ($1.12{\pm}1.43mm,\;4.01{\pm}2.36mm$) from the midwaist point, and there is no correlation between antilingular prominence and lingular, mandibular foramen.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.17 no.1
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• pp.163-171
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• 1987

The author has clinically and radiologically investigated 57 cases of odontogenic keratocyst in 47 patients consisted of 26 males and 21 females aged from.2 to 63 years, who were pathologically diagnosed as odontogenic keratocyst at infirmaries of dental colleges, Yonsei University and Seoul national university during 1965-1986. The results were as follows: 1. The peak incidence of the disease was on their teenagers (29.8%). The ratio of Male/Female was 1.23:1 and incidence rate of males showed higher than their counterpart. 2. The most frequent complaints were swelling in (65.9%) followed by pus discharge, unknown mass, pain, residual root. 3. The most common site was mandibular third molar and mandibular ramus region (15.8%) followed by mandibular body and ramus, mandibular third molar, mandibular anterior teeth. Incidence of this disease in mandible was higher than in maxilla. 4. The lesions not associated with adjacent teeth were (14.0%) and in the lesions associated with adjacent teeth (35.1%) showed root resorption, (50.9%) were without root resorption, (35.1%) showed tooth migration and (50.9%) were without tooth migration. 5. The border types of the lesions were scalloped type in (52.6%), smooth type in (47.4%) and morphological type were unilocular in (50.9%), multilocular in (49.1%). 6. The radiologic cyst type of the lesions were follicular type (42.1%) followed by primordial, unclassified odontogenic, residual, lateral periodontal, median mandibular, globulomaxillary type.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.4
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• pp.271-281
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• 2006

Long term prediction of surgical result of skeletal class III has not been evaluated adequately because the stability of orthognathic surgery would be affected by not only set back amount of mandible but also many other factors like skeletal pattern, hyoid position, and airway size. The aimof this study is to discriminate the factors which affect the stability of post-treatment result of surgical outcome of sagittal split ramus osteotomy. We have collected 37 patients (male: 17, female: 20) from patients who have been treated at Orthodontic Department in Dankook University. The patients underwent 3 times Cephalometric X-ray taking at pre-, post-orthognathic surgery and after 12 months retention. The subjects were divided into 2 groups (Stable group: 21, Relapse group: 16) according to their relapse amount. We have taken following results from Students t-test and discriminant analysis. The discriminant factors which discern relapse and stable groupe among treatment change variables were BX and Ba-HY. Hyoid bone moved to posterior and inferior position due to surgery and repositioned superiorly and posteriorly during retention period. Skeletal patterns of the relapse group are smaller mandibular plane angle, anterior mandibular position, and greater distance from hyoid bone to cervical bone and mandible respectively.

• Archives of Craniofacial Surgery
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• v.18 no.1
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• pp.65-70
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• 2017

A 25-years-old woman with mandibular prognathism underwent a mandibular setback by way of mandibular sagittal split ramus osteotomy (MSSRO). After 2 days of operation, she developed difficulty of closing her right eye. The blink reflex test and motor nerve conduction study of the right orbicularis oris muscle were revealed right facial neuropathy of unknown origin and House-Brackmann facial nerve grading system (HBFNGS) grade V. For treatment, we initially prescribed oral prednisolone and nimodipine including physical therapy. The samples consisted of 11 facial nerve palsy patients caused by MSSRO and were analysed about onset of facial nerve palsy, postoperative HBFNGS, final HBFNGS, treatment method and recovery time. At 10 weeks of treatment of nimodipine, she had completely regained normal function (HBFNGS grade I) of the right facial nerve. The clinical results lead to assume a fast recovery of facial nerve function by the nimodipine medication, whereas average time of recovery is 16.32 weeks in references. Despite of the limited one patient treated, the result was very promising with respect to a faster recovery of the facial nerve function. Considering the use of nimodipine treatment for peripheral facial nerve palsy following a surgical approach with an anatomically preserved nerve can be recommended.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.1
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• pp.100-107
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• 2008

First of all a good surgical access is considered among various approach methods to the cystic lesion. A poor surgical access can lead to a failure of the whole treatment. A sagittal split ramus osteotomy (SSRO) on the large cyst occurring in the mandibular ramus lets us not only reduce operation time, but can additionally contribute to a good visual field. In addition, a merit exists that it lets this operating method provide soft tissue adhesion for proximal and distal segment and decrease post operative necrosis. We experienced three cases of a large cyst on the mandibular angle and ramus. By employing a sagittal splitting of the mandible, it provided good surgical access and operation results without recurrence during a follow-up period. The surgical technique described may be helpful in treating similar large cysts.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.4
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• pp.351-358
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• 2010

A 31-year-old woman with hemifacial microsomia presented to the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. The patient was previously treated with distraction osteogenesis device to elongate right maxilla and mandibular ramus. But, the result was not satisfactory, to correct residual facial asymmetry due to hemifacial microsomia we planned costochondral graft for reconstruction of ramus and condyle, Le Fort I osteotomy and sagittal split ramus osteotomy for facial asymmetry. The right mandibular condyle and ramus was reconstructed with right eleventh costochondral graft via submandibular approach. Using costochondral graft and orthognathic surgery the facial asymmetry in hemifacial microsomia patient was corrected. 1-stage treatment consists of costochondral graft and orthognathic surgery can achieve function and esthetics at the same time, is timesaving to both patient and surgeon.

• Imaging Science in Dentistry
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• v.46 no.3
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• pp.223-227
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• 2016

A static, unilateral, and focal bone depression located lingually within the ascending ramus, identical to the Stafne's bone cavity of the angle of the mandible, is being reported. During development of the mandible, submandibular gland inclusion may lead to the formation of a lingual concavity, which could contain fatty tissue, blood vessels, or soft tissue. However, similar occurrences in the ascending ramus at the level of the parotid gland are extremely rare. Similar cases were previously reported in dry, excavated mandibles, and 3 cases were reported in living patients. A 52-year-old African American male patient was seen for pain in the mandibular teeth. Panoramic radiography showed an unusual concavity within the left ascending ramus. Cone-beam computed tomography confirmed this incidental finding. The patient was cleared for the extraction of non-restorable teeth and scheduled for annual follow-up.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.1
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• pp.32-36
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• 2014

Preoperative surgical simulation in orthognathic surgery has progressed in recent years; the movement of the mandible can be anticipated through three-dimensional (3D) simulation surgery before the actual procedure. In this case report, the mandible was moved to the intended postoperative occlusion through preoperative surgical 3D simulation. Right-side condylar movement change was very slight in the surgical simulation, suggesting the possibility of mandibular surgery that included only left-side ramal osteotomy. This case report describes a patient with a mild asymmetric facial profile in which the mandibular menton had been deviated to the right and the lips canted down to the left. Before surgery, three-dimensional surgical simulation was used to evaluate and confirm a position for the condyle as well as the symmetrical postoperative state of the face. Facial asymmetry was resolved with minimal surgical treatment through unilateral intraoral vertical ramus osteotomy on the left side of the mandible. It would be a valuable complement for the reduction of the surgical treatment if one could decide with good predictability when an isolated intraoral vertical ramus osteotomy can be done without a compensatory osteotomy on the contralateral side.