• Archives of Plastic Surgery
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• v.36 no.4
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• pp.475-480
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• 2009

Purpose: To correct the facial asymmetry and to achieve symmetry and balance, not only the soft tissue restoration of deficits but also creation and facial contour line such as mandible border and angle is important. Micro fat graft has limitation such as high resorption rate and somewhat limited ability to emphasize the rigid bony characteristics of the mandible angle due to its innate soft consistency. We have investigated the advantages of dermal fat graft over micro fat graft to correct asymmetry of the lower face in patients who had undergone mandibular reconstruction or distraction, using comparative analysis. Methods: Total of 12 patients were enrolled in our study: 6 micro fat graft and 6 dermal fat graft. Postoperative results were compared and analyzed at immediate postoperative period and more than 1 year later in each group with photographs, and analysised with image J program. Result: No complications were noted both in the micro fat type and the dermal fat type of procedures such as fat necrosis or micro calcifications. All of the patients who received micro fat graft, however had considerable amount of fat resorption after the procedure which led to two additional fat graft procedures. Although minor contour obliteration due to contracture was seen in patients who had undergone dermal fat graft procedure, no definite resorption was found even after more than one year follow-up. Results of dermal fat graft patients were satisfactory in terms of mandible angle symmetry. Secondary revision was necessary in one case due to overcorrection using dermal fat graft. Conclusion: The dermal fat graft has many advantages over the conventionally more popular micro fat graft to correct asymmetry of the lower face following mandible reconstruction owing to its lower resoption rate, more effective in emphasizing the natural curvilinear anatomical contours of the mandible angle and body and lower complication rates such as fat necrosis or micro calcifications.

• Imaging Science in Dentistry
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• v.42 no.2
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• pp.65-70
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• 2012

Purpose : The aim of this study was to compare the effective dose for imaging of mandible between multi-detector computed tomography (MDCT) and cone-beam computed tomography (CBCT). An MDCT with low dose technique was also compared with them. Materials and Methods : Thermoluminescent dosimeter (TLD) chips were placed at 25 organ sites of an anthropomorphic phantom. The mandible of the phantom was exposed using 2 different types of MDCT units (Somatom Sensation 10 for standard-dose MDCT, Somatom Emotion 6 for low-dose MDCT) and 3 different CBCT units (AZ3000CT, Implagraphy, and Kavo 3D eXaM). The radiation absorbed dose was measured and the effective dose was calculated according to the ICRP 2007 report. Results : The effective dose was the highest for Somatom Sensation 10 (425.84 ${\mu}Sv$), followed by AZ3000CT (332.4 ${\mu}Sv$), Somatom Emotion 6 (199.38 ${\mu}Sv$), and 3D eXaM (111.6 ${\mu}Sv$); it was the lowest for Implagraphy (83.09 ${\mu}Sv$). The CBCT showed significant variation in dose level with different device. Conclusion : The effective doses of MDCTs were not significantly different from those of CBCTs for imaging of mandible. The effective dose of MDCT could be markedly decreased by using the low-dose technique.

• Imaging Science in Dentistry
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• v.43 no.4
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• pp.227-233
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• 2013

Purpose: This study was performed to analyze human maxillary and mandibular trabecular bone using the data acquired from micro-computed tomography (micro-CT), and to characterize the site-specific microstructures of trabeculae. Materials and Methods: Sixty-nine cylindrical bone specimens were prepared from the mandible and maxilla. They were divided into 5 groups by region: the anterior maxilla, posterior maxilla, anterior mandible, posterior mandible, and mandibular condyle. After the specimens were scanned using a micro-CT system, three-dimensional microstructural parameters such as the percent bone volume, bone specific surface, trabecular thickness, trabecular separation, trabecular number, structure model index, and degrees of anisotropy were analyzed. Results: Among the regions other than the condylar area, the anterior mandibular region showed the highest trabecular thickness and the lowest value for the bone specific surface. On the other hand, the posterior maxilla region showed the lowest trabecular thickness and the highest value for the bone specific surface. The degree of anisotropy was lowest at the anterior mandible. The condyle showed thinner trabeculae with a more anisotropic arrangement than the other mandibular regions. Conclusion: There were microstructural differences between the regions of the maxilla and mandible. These results suggested that different mechanisms of external force might exist at each site.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.1
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• pp.71-92
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• 1999

This study is to analyze the stress and displacement on the jaws during the bilateral and unilateral clenching task on three dimensional finite element model of the dentated skull. For this study, the computed tomography(G.E.8800 Quick, USA) was used to scan the total length of human skull in the frontal plane at 1.9mm intervals. The CAD data were extracted from the tomograms through digitizer(Summa Sketch III, USA) and then reconstructed by means of the spline method in the CAD program. In this project, a commercial software I-DEAS(Master Series ver-sion 3.0, SDRC Inc, USA) was used for three-dimensional stress analysis on the finite element model. which consists of articular disc, maxilla, mandible, teeth, periodontal ligament and cranium. The results are as follows. ; 1. During the bilateral clenching, each major muscle forces caused high stresses on various areas of skull: masseter muscle on articular disc and teeth ; temporal muscle on mandible and periodontal ligament ; medial pterygoid muscle on the temporomandibular joint. During the unilateral clenching, masseter muscle induced the maximum stress ; medial pterygoid muscle the minimum stress. 2. During the bilateral clenching, higher compressive stresses on articular disc were generated by the masseter muscle and higher deformation occurred on the most front outer sites. And during the unilateral clenching, temporal muscle and medial pterygoid muscle exerted their forces to twist temporomandibular joint area of the balancing side and induced a higher compressive stresses on the front outer sites of articular disc. 3. During the bilateral clenching, the masseter muscle bended the mandible outwardly, and then caused tensile stresses on the lingual surface of mandibular symphysis. And the medial pterygoid muscle caused tensile stresses on the labial surface of mandibular symphysis. 4. When each muscles were simultaneously applied on jaws, a high stress and displacement took place on mandible rather than on the maxilla. Also, a high stress and displacement took place during the unilateral clenching rather than during the bilateral clenching.

• The korean journal of orthodontics
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• v.12 no.1
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• pp.21-26
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• 1982

This study was undertaken to document relations between facial skeletal pattern and dental occlusion. The data in .this study were collected from pretreatment cephalometric radiographs and study models of patients' records present in the files of Orthodontic Department, Seoul National University Hospital. Patients were selected on the basis of a mandibular plane-sella nasion angle equal to or greater than $38^{\circ}$ (high SN-MP angle) or equal to or less than $26^{\circ}$ (low SN-MP angle). Patients in the mixed dentition and with missing permanent teeth were excluded for ease of assessing tooth size / arch circumference relationships and then 30 high SN-MP and 11 low SN-MP patients were selected among them. The mean age of these two groups of patients was high SN-MP, $12.8{\pm}1.23$ years and low SN-MP, $13.0{\pm}1.48$ years. The following conclusions were obtained. 1. In the maxilla and mandible the mean tooth size of high SN-MP patients was nearlly identical to the low SN-MP patients. 2. The mean maxillary arch circumference was increased in low SN-MP group compared with high SN-MP group and a smilar, but smaller, mean increase was present in mandible. 3. The difference between the mean maxillary circumference required and the mean maillary circumference present ranged from -4.8mm in the high SN-MP group to -1.3mm in the low SN-MP group. A small range of means occurred in the mandible (high SN-MP: -4.0mm to low SN-MP: -1.8mm). 4. In the maxilla and mandible the mean arch length was nearly identical in the high and low SN-MP groups. 5. The mean incisor inclination was increased as the SN-MP angle decreased in the maxilla and mandible. 6. The men distance of the maxillary first molar from anterior border of the pterygomaxillary fissure was nearly similar between high and low groups. 7. The mean mandibular intermolar width was increased from high SN-MP to low SN-MP patients.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.521-541
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• 1991

The purpose of this study was to investigate the growth changes of the mandible and associated structure in response to postural hyperpropulsion and changes after removal of postural hyperpropulsor. The experimental animals were four-week-old Sprague-Dawley males rats. The animals were worn the postural hyperpropulsor diurnally for 10 hours per day. The animals were sacrified after 1-week, 2-week, 4-week postural hyperpropulsion and 4-week postural hyperpropulsion 4-week removal period. The growth changes of rat mandible and associated structures following postural hyperpropulsion on the growing rat mandible were observed biometrically, radiographically and histologically. The finding were as follows. 1. The angle between the chief axis of the bone trabeculae in the condyle and the mandibular plane of rats observed for 4 weeks after worn the hyperpropulsor for 4 weeks was directed posteriorly as compared with that of control rats. 2. The ratio of mandibular length to maxillary length of experimental rats was higher than that of control rats. 3. The tooth axis of mandibular first molar of rats worn the postural hyperpropulsor for 4 weeks was mesially inclined as compared with control rats. 4. Histologically, the cartilage layer at the superior region of the condyle of rats worn the postural hyperpropulsor for 2 weeks appeared thicker than that of same aged normal rats, and generalized increase of the cartilage layer was shown on the condyle of rats worn the postural hyperpropulsor for 4 weeks. 5. There was no significant histologic difference between rats observed for 4 weeks after worn the postural hyperpropulsor for 4 weeks (8 week experimental rats) and same aged normal rats. 6. The newly formed bone at anterior region of articular fossa of rats worn the postural hyperpropulsor for 2 weeks and 4 weeks was thicker than that of same aged normal rats.

• Journal of Periodontal and Implant Science
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• v.36 no.2
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• pp.489-502
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• 2006

The purpose of this study was to determine the relationship between the third molar and periodontal status of the adjacent second molar. Fifty patients who had four maxillary and mandibular second molars were consecutively selected for the study subjects. The subjects provided a total of 200 molars, i. e., 100 maxillary and 100 mandibular molars, and classified the groups as follows; third molars that are normally erupted are control group, that are impacted are test 1 group, that are simply extracted are test 2 group, that are surgically extracted are test 3 group. Probing depth, plaque index, gingival index and mobility were measured. The results were as follows. 1. In mesial probing depth, there was no significantly difference. In distal probing depth, there was a significantly difference between control group and test 1 & 3 group in maxilla and between control & test 2 group and test 1& 3 group in mandible(p<0.05). 2. In buccal probing depth, there was a significantly difference between test 2 group and test 3 group in mandible. In lingual probing depth, there was a significantly difference between control group and test 1 & 3 group in mandible(p<0.05). 3. In plaque index, there was a significantly difference between test 1 group and test 2 group in maxilla, between test 1 group and control & test 2 group in mandible(p<0.05). 4. In gingival index, there was a significantly difference between control group and test 1 & 3 group in mandible. In mobility, there was no significantly difference(p<0.05). As a result of this study, the second molars adjacent to the third molars that are impacted or surgically extracted had poor prognosis, so impacted third molars should be extracted in early time and the second molars are actively treated for periodontal health.

• Imaging Science in Dentistry
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• v.49 no.1
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• pp.9-17
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• 2019

Purpose: This study aimed to introduce a novel method to evaluate the alveolar bone and interdental septum in the anterior mandible using cone-beam computed tomography (CBCT). Materials and Methods: Fifty-six CBCT scans from adult patients were selected. The CBCT scans were obtained before and after orthodontic treatment. The following measurements were taken: width of the alveolar bone and the interdental septum, height of the interdental septum, height of the bone plates, distance between the cementoenamel junction and marginal bone crests, and vertical positioning of the mandibular incisor, using the lingual plane as a reference. To test the reproducibility and the stability of the lingual plane, a triangle was traced in the anterior mandible. The intra-class correlation coefficient(ICC) was used to determine intra- and inter-examiner agreement. The paired Student t-test was used to evaluate the area of the triangle and the reproducibility of all measurements. Results: The ICC was excellent for the alveolar bone and dental measurements (0.9989 and 0.9977, respectively), as well as for the interdental septum (0.9987 and 0.9961, respectively). The area of the triangles showed stability in the lingual plane (P>0.05). For the alveolar bone, mandibular incisor, and interdental septum measurements, no statistically significant differences were found between the 2 examiners(P>0.05), confirming the technical reliability of the measurements. Conclusion: The method used in this study provides a valid and reproducible assessment of alveolar bone dimensions in the anterior mandible measured on CBCT images.

• Imaging Science in Dentistry
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• v.37 no.4
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• pp.221-223
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• 2007

The radiographic diagnosis of typical Stafne bone cavity could be done easily with cyst-like round or oval radiolucency near the angle of the mandible, under mandibular canal with or without involving mandibular base, and no symptoms. However there are some atypical cases suggesting possible variations of this entity. We report a quite unusual case, where Stafne bone cavity was lastly included in the differential diagnosis list. Histological examination of salivary gland tissues confirmed the final diagnosis.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.19 no.2
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• pp.200-208
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• 1997

The WHO separates odontogenic carcinomas into three groups : malignant ameloblastoma, primary intraosseous carcinoma(PIOC), and carcinomas arising from odontogenic epithelium including those arising from odontogenic cysts. In WHO criteria, primary intraosseous carcinoma is defined as a squamous cell carcinoma arising within the jaw, having no connection with the oral mucosa, and no developing from residues of odontogenic epithelium. This is a case of 52-year old man who had prolonged jaw pain and final diagnosis was primary intraosseous carcinoma(PIOC) on mandible. We obtained successful result after composite resection combined with hemimandibulectomy, RND, following reconstruction with latissmus dorsi myocutaneous flap, and postoperative radiation therapy.