• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.4
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• pp.319-322
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• 2011

Purpose: The purpose of this study was to examine the appropriate degree of set-back of the mandible by evaluating the rate of relapse after surgery. Methods: Among the patients who visited our hospital from January 2002 to January 2007 and who underwent orthognathic surgery, of the patients available for follow-up observation, the rate of relapse after surgery was investigated according to the set-back degree. The patients were divided into groups by the degree of set-back, and relapse was evaluated by the radiographs performed the day after surgery, 6 months after surgery, 1 year after surgery, 2 years after surgery and 3 years after surgery. Results: In cases that exceeded the limit of posterior movement of the mandible (13 mm) or that had the wrong position of the condyle, a greater tendency toward relapse was shown. Conclusion: Based on the results of this study, among the cases that required a large amount of posterior movement of the mandible, two jaw surgeries accompanied by bilateral sagittal split ramus osteotomy (BSSRO) and LeFort I osteotomy are recommended.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.43-53
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• 1999

Purpose: The aim of this study was to analyze radiologically the location and course of the mandibular canal and to observe the alveolar and basal bone changes during the remodeling procedures of atrophic mandible. Materials and Methods: CT scanning was performed on dry 30 edentulous or partially dentulous mandibles. In 48 edentulous lower halves, measuring areas were determined by three points in the length of the mandibular canal. The distance from the mandibular canal towards cranial and caudal edges, buccal and lingual external borders of the body of the mandible were measured. A statistical comparison between the mean values of different classes of mandibular body was carried out in the selected areas. Results: The distance between the mandibular canal and caudal borders of the body of the mandible and lingual borders dose not change in the atrophic process of mandible. The mandibular canal within the mandible courses downwards from mandibular foramen towards mesial and subsequently it gets to the mental foramen. The distance between the mandibular canal and buccal external border of basal bone changes similar to the change of cranial borders of alveolar bone in the atrophic process of mandible. Conclusion: CT scanning was very effective and practicable to analyze the location and course of the mandibular canal and to observe the alveolar and basal bone changes of atrophic mandible. Also more detailed investigation of basal bone changes observed during the remodeling procedures of atrophic mandibles seems reasonable to rely on the massive anthropologic collections of atrophic mandibles combined with CT scanning.

• The korean journal of orthodontics
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• v.19 no.3
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• pp.15-33
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• 1989

The purpose of this study was to investigate changes of the mandible of a growing rat when they are subjected to a retractive force and those after removal of the retractive force. The experimental animals were Sprague-Dawley male rats of four weeks of age. A mandible was retracted with 50 grams of force on each side in the posterior and superior direction for 8 hours per day. The animals were sacrificed after 1 week, 2-week and 4-week force application, and after 4-week force application-4-week force removal period. The changes of rat mandibular growth following retractive force on the growing rat mandible were observed histologically and biometrically. The findings were as follows ; 1. Histologically, the thickness of the condylar cartilage was slightly reduced in the anterosuperior region with the retractive force. However, in the group of 4-week force application-4-week force removal, there was no significant difference in the thickness of the condylar cartilage. 2. There were no significant histological changes in the articular disk and glenoid fossa through the experimental period. 3. The length and anterior height of the mandible subjected to the retractive force were significantly smaller and greater than those of the control group. 4. There were no significant differences in the mandibular length between 4-week force application - 4-week force removal and the control group. 5. It was concluded that a mandibular retractive force produced inhibitory effects in the growth of the mandible, but that these effects were not sustained during mandibular growth in this experimental model.

• Journal of Oral Medicine and Pain
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• v.49 no.2
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• pp.29-34
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• 2024

Acute malocclusion can occur in conditions related to temporomandibular joint (TMJ) disorders. This report presents two cases of acute malocclusion related to posterior disc displacement according to complete disc tearing. A 65-year-old male and an 88-yearold female presented with TMJ pain and occlusal discrepancies. Clinical examination, computed tomography, and magnetic resonance imaging revealed complete disc tearing and posterior displacement of a partial disc fragment. Dental cast analysis revealed a slight anterior and lateral deviation of the mandible toward the non-affected side; however, clinically, significant occlusal changes were not observed. This was attributed to the displacement of a small disc fragment rather than the entire disc. Including the cases presented, most instances of complete disc tearing responded well to conservative treatment such as pharmacotherapy and physical therapy, resulting in pain alleviation, and residual occlusal changes were tolerable for the patients in their daily activities. However, persistent occlusal changes or severe chewing difficulty may require surgical intervention.

• Journal of Oral Medicine and Pain
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• v.9 no.1
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• pp.51-64
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• 1984

In order to obtain the basic data of movements of the mandible for diagnosis and prgnosis determination of the TMJ dysfunction, the author measured the ranges and shapes of movements of the mandibule in the frontal, sagittal and horizontal trajectory with Saphon Visi-Trainer C-Ⅱ(Tokyo Shizaisha Inc.) in 61 men. The subjects who were undergraduate and graduate students of the School of Dentistry, Seoul Nationa University(SNU) had no pain or symptoms of dysfunction of the masticatory system. The obtained results were as follows: 1. The mean for maximal right and left laterotrusion in the frontal trajectory were 11.3 mm and 10.9mm, respectively and didn't differ significantly. Right and left larero-opening at 15mm, 25mm and 35mm mouth opening respectively didn't differ significantly. Area of border movement of the mandible was 770.33㎟. 2. The mean for maximal protrusion in the sagital trajectory was 10.2mm, antero-posterior deviation between ICP and RCP 1.2mm and angel of maximal protrusion and horizontal plane 20.5。. 3. The mean for right and left laterotrusion is 11.1mm &11.2mm,respectively, and didn't diffef significantly.

• Imaging Science in Dentistry
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• v.52 no.2
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• pp.231-238
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• 2022

Intraosseous xanthoma of the mandible is a rare benign disorder. A 17-year-old male patient presented with a suspected abscess in the right mandibular third molar, detected on a panoramic radiograph. The patient had no history of systemic or lipid-related metabolic diseases and complained of no specific symptoms or pain. A radiographic examination revealed a heterogeneous radiolucency extending from the apical to the distal aspect of the right mandibular third molar tooth germ. The lesion measured 9 × 16 × 24 mm (antero-posterior × mediolateral × supero-inferior) and showed a relatively well-defined, multilocular, foamy appearance with hyperostotic borders spreading to the inferior alveolar nerve canal. After excisional biopsy, a diagnosis of central xanthoma was made. The lesion recurred, and intraoral vertical ramus osteotomy was done near the lesion. For the treatment of xanthoma of the mandible, extensive and delicate surgical treatment under general anesthesia should be considered.

• The korean journal of orthodontics
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• v.19 no.1 s.27
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• pp.45-59
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• 1989

This study was undertaken to analyze the displacement and stress distribution in the mandible according to the pulling directions during mandibular first molar cervical traction after mandibular second molar extraction. The 3-dimensional finite element method(FEM) was used for a mathematical model composed of 594 elements and 1019 nodes. An orthodontic force, 450 gm, was applied to the each mandibular first molar in parallel, and below the occlusal plane by $7^{\circ}\;and\;25^{\circ}$ and meet the midsagittal plane by $40^{\circ}$ toward posterior direction. The results were as follows: 1. Mandibular teeth were displaced in more downward, posterior and lateral direction. Especially high stress was noted in case of parallel pull than in case of below the occlusal plane by $7^{\circ}\;and\;25^{\circ}$. 2. Mandibular first molar was moved bodily. 3. Generally, alveolar bone, mandibular body, ascending ramus and mandibular angle portion were displaced in downward, posterior and lateral direction. But coronoid process was displaced in downward, forward and lateral direction, and anterior and inner middle portion of condyle head and neck were displaced in downward, forward and medial direction, and posterior and outer middle portion of condyle head and neck were displaced in upward, forward and medial direction. 4. Maximum stress was observed at the condyle head and neck portion. With steeper direction of force, condyle head and neck showed more stress than parallel relation to the occlusal plane.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.2
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• pp.75-84
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• 2001

The purpose of this study is to to analyze the mechanical stress on articular disk of the dentated skull with the condition of unilateral posterior molar missing. For this study, the three dimensional finite element model of human skull scanned by means of computed tomography. (G.E. 8800 Quick, USA) was constructed. The finite element model of jaws is composed of 98,394 elements and 38,321 nodes, and it consists of articular disc, maxilla, mandible, teeth, periodontal ligament and cranium. Boundary condition included rigid restraints at the first molar and endosteal cortical surfaces of the insertion points of temporal bone. The data derived from Nelson's study were used for the loading conditions of mandible during clenchings and for maxilla, new loading and constraint conditions were applied. A clenching task during intercuspal position was modeled to the three dimensional finite element model. The stress level and displacement of articualr disc on the model with unilateral posterior molar missing under bilateral clenching task can be analyzed. During bilateral clenchings, the compressive stress level and diplacement of the articular disk on the side of unilateral posterior molar missing is greater than that on the case with full dentition, whereas a higher stress was found on the disk on the balancing side of the full dentition. Although this kind of study is not enough to explain the role of occlusion as an etiologic factor of TMD, there may be a possibiliy that the condition of posterior molar missings may contribute in part to the TMJ biomechanics.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.141-154
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• 1988

This study was designed to investigate the difference between craniofacial characteristics of the normal occlusion and those of Class II Div. 1 malocclusion. The sample was divided into 2 groups, the 50 subjects of Normal occlusion, the 50 subjects of Class II Div. 1 malocclusion in both sexes. Both groups aged from 11 to 14 years. The results of this study were as follows; 1. No significant difference was observed in cranial base shape between both groups, but anterior cranial base size of Class II Div. 1 malocclusion group was larger than that of normal group. 2. No significant difference in antero-posterior position of Maxilla to cranial base was founded between both groups. 3. No difference in Mandibular shapes and Mandibular plane angles to the cranial base was observed between Class II Div. 1 malocclusion and normal occlusion, but Mandibular position in Class II Div. 1 malocclusion was posterior to that of normal group. 4. Antero-posterior relationship of Maxilla and Mandible was significant difference between both groups, but vertical relationship of those was no difference. 5. Maxillary incisor position to cranial base of Class II Div. 1 malocclusion was anteior to normal occlusion, and Maxillary posterior teeth was posterior. Mandibular incisor and mandibular posterior teeth position was no difference. 6. Upper and lower lip position to esthetic line of Class II Div. 1 malocclusion was anterior to normal occlusion.

• The Journal of the Korean dental association
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• v.5 no.1
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• pp.60-62
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• 1964

The Author have had a case of Salivary-stone in the posterior of Warton's duct in the right Side . 1. The patient was 24 years-old R.O.K.a Soldexr. 2. The salivary stone was 1.6cm by 2.11 cm in big size. 3. There was a History of pain at meal-time, and swelling of mandible of Right region.