• PNF and Movement
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• v.16 no.1
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• pp.115-123
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• 2018

Purpose: The aim of this study was to investigate the effect of mandible position on proprioception and range of motion (ROM) during neck stabilization exercise using a sling in healthy adults. Methods: The subjects were randomly assigned to either a sling exercise and mandible open group (n=10) or a sling exercise and mandible closed group (n=12). The sling exercise-mandible open group and sling exercise-mandible closed group took part in an exercise program for 30min, three times per week for 4 weeks. After each training session, head repositioning accuracy (HRA) and the ROM of the cervical spine were measured. Wilcoxon's test was conducted to verify changes within each group, and the Mann-Whitney U test was performed to examine between-group differences. Results: The HRA of the cervical spine was significantly increased during left rotation and extension in the sling exercise-mandible open group. In addition, there were significant differences in both rotations and extension in the two groups. The ROM of the cervical spine increased significantly during both rotations in the sling exercise-mandible closed group. In addition, there was a significant difference in right rotation and extension in both groups. Conclusion: Cervical stabilization exercise using a sling, with the mandible closed increased proprioception and the ROM of the cervical spine.

• Journal of Mechanical Science and Technology
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• v.15 no.7
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• pp.974-981
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• 2001

One approach to reconstructing a damaged mandibular condyle is to replace it with a rib graft. This procedure requires removal of the lateral pterygoid muscle. The rib graft has significantly different shape and mechanical properties than the original condyle. These three factors can be expected to alter mandible (jaw) mechanics. We used voxel-based finite element methods to analysis both normal and a simulated reconstructed mandible using data from the US NIH Visible Human Female. Results demonstrated significant differences between normal and reconstructed mandible mechanics. The reconstructed mandible displaced more than the normal mandible. Stresses in the rib graft were 3 to 4 times higher than in a normal mandibular condyle. Stresses in the rest of the mandible were also higher in the reconstructed case. Further analyses are required to determine how each of the alterations in the reconstructed mandible contributes to the difference in reconstructed mandible mechanics.

• The korean journal of orthodontics
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• v.20 no.1
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• pp.183-195
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• 1990

The purposes of present study were to identify possible relationships between post-treatment changes and post-retention changes. The patient's models were composed of 58 samples, and were classified non-extraction group (30 samples) and extraction group (28 samples). For each sample the first models were taken prior to the start of treatment, the second models just after the end of treatment, and the third models two years after. The results were as follows: 1. In the cases of non-extraction group, increases were in intermolar width of maxilla, interbicuspid width of maxilla and arch perimeter of mandible during treatment period, but decreases were in the same measurements during post-retention period. 2. In the cases of extraction group, decreases were in intermolar width of mandible, interbicuspid widths of maxilla and mandible, arch length of mandible, arch perimeters of maxilla and mandible during treatment period. 3. Significant decreases were in the irregularity index of both extraction and non-extraction group during treatment period. 4. There were significant differences of arch dimensional changes in intermolar widths of maxilla and mandible, interbicuspid widths of maxilla and mandible, arch lengths of maxilla and mandible, arch perimeters of maxilla and mandible between non-extraction and extraction group.

• The korean journal of orthodontics
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• v.8 no.1
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• pp.59-71
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• 1978

The author compared and analysed the roentgenocephalograms of one hundred Korean adults with the normal occlusion (50 males and 50 females), which were taken on the centric occlusion and the rest position of the mandible respectively for every subject, and then researched the relations among the relaxed muscle of the mandible, lightly touched of the lips, and the position just after the swallowing of saliva, of which 38 among 50 males had the rest position of the mandible. The results are as followings: 1. The anterior facial height increases more at the rest position of the mandible than at the centric occlusion, while the posterior facial height decreases. 2. The mandible moves more backward and downward at the rest position of the mandible than at the centric occlusion. 3. The facial procumbency and the incisor tooth inclination increases more at the rest position of the mandible than the centric occlusion in terms of the facial plane. 4. There are no differences between males and females at the rest position of the mandible and the centric occlusion in the meaning of variation. 5. There are no differences among the three methods from the view of lines and angles of the roentgenocephalogram.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.3
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• pp.470-487
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• 1996

The purpose of this study was to investigate the dynamic response of the mandible to impact and provide insight into the fracture mechanism of the mandible, by 3-dimensional finite element method. The finite element model of the mandible was developed and calculated using NASTRAN/XL (MSC co. U.S.A.) and the linear dynamic transient analysis was performed according to the impulsive force direction, force type and impulse time to the mandible. At first, the load was applied on the mandibular symphysis, body, angle and subcondylar area in the horizontal mandibular plane and the computed stress-time histories at 14 locations of the mandible were obtained. Secondly, the impulsive force was directed to the symphyseal area with changing the force magnitude and impulse time, and calculated the node displacement at 8 locations of mandible. The conclusions from from this study were as follows. 1. The appearance of impulsive energy transmission was different to the direction of impulse to the mandible. 2. The impulsive stress and deformation were larger in lingual or medial side than buccal or lateral in the mandible. 3. The velocity, appearance of energy transmission and the fracture pattern in mandible were affected rather impulse time than force. 4. The horizontal impact to the one side of mandible did not have effect on the stress and displacement of contralateral mandible. From the above results, fracture pattern in symphysis can be showed as simple or comminuted, multiple or associated in body and angle and solitary in subcondyle area.

• Korean Journal of Head & Neck Oncology
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• v.18 no.2
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• pp.223-226
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• 2002

The segmental mandibulectomy should be performed, if mandiblie invasion is suspected clinically and radiologically. And if tumor is located to mandible very closely or when microinvasion to mandible is suspected, marginal mandibulectomy is recommended. But in segmental mandibulectomy, reconstruction is difficult and cosmetic problem remains. In this case, we performed modified segmental resection of mandible, preserving the inferior margin of mandible, and maintains the continuity of the bone, in mucoepidermoid carcinoma of parapharynx, invading mandible. We reviewed the diagnosis, pathology, and treatment, and report the case with reviews of literature.

• Archives of Craniofacial Surgery
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• v.11 no.1
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• pp.45-48
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• 2010

Purpose: After surgical interventions of mandible fractures, facial asymmetry can be occurred, and it leads to serious problems for patients. This can be solved by mandible angle ostectomy. Methods: A 19-year-old male underwent percutaneous surgical intervention for left mandibular angle and right parasymphyseal fractures 3.5 years ago. The left angle was protruded compared to the other side. Using a percutaneous approach, $4.5{\times}1cm$ sized piece of mandible angle was sawed off. For the right angle, intraoral approach was performed for angle ostectomy, and the angle was sawed off by a size of $4{\times}1cm$, using a pattern based on the piece from the left side. Results: After surgery, no complications such as subcondylar fractures, refractures, insufficient corrections, secondary angle formations, hematomas, and transient nerve palsies were seen, and symmetric correction of mandible angles were done. Conclusion: In facial asymmetries due to mandibular fractures, mandible ostectomy could be a solution. Using the bone section from the contralateral side, measurement of the amount of bone sawed off was possible, and via percutaneous approach on the previously operated site with simultaneous scar revision, and intraoral approach for the contralateral side, cosmetically satisfactory result was obtained.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.1
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• pp.12-25
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• 2000

To demonstrate possible influences of general bone density on the mandible, histomorphometric analysis was carried out in mandibles and iliac bones and the correlation of the two bone densities was tested. Comparison of bony density in women and men over 60 years in the mandible was carried out too. Quantitative computed tomography(QCT) was taken in cross-section of mandibles at the same site where histomorphometric analysis was peformed to evaluate the reliability of QCT. The analysis included 40 cadavers with no known diseases affecting the bones. The subjects consisted of 15 females and 25 males with a mean age of 60.3 years. Spearman correlation analysis and Wilcoxon rank sum test was performed. The results were as follows. 1. There was statistically no correlation between the mandible and iliac bone in the values of corrected cortical width(CCW), cortical porosity(POR) in cortex, and total bone volume(TBV), mean trabecular plate thickness(MTPT), mean trabecular plate density(MTPD), and mean trabecular plate separation(MTPS) in trabecular bone. 2. Comparison of women and men over 60 years, men had statistically higher bone density than women except fir POR of buccal and lingual cortex, and WTPD of alveolar trabeculae in mandible. 3. There was statistically significant correlation between TBV of trabecular bone and CT No., but not between POR and CT No. in mandible. According to the results above, there was no correlation between mandible and iliac bone density and between mandibular bony density and age. Further studies are required to support the results. A more noninvasive method to be able to measure the bone density of mandible should be developed and it is necessary to accumulate data on the normal values of bone density of mandible according to age and sex. Further study should be carried out about QCT to measure mandibular bony density using QCT.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.1
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• pp.34-40
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• 2012

Purpose: The study was performed to compare patients with anatomical variations in facial asymmetry with patients in the normal range using cone-beam computed tomography (CBCT) and to take the preoperative condition into consideration in the case of a sagittal split ramus osteotomy (SSRO). Methods: The study was conducted on 46 adult patients composed of 2 subdivided groups, an asymmetry group (n=26) and a symmetry group (n=20). The asymmetry group was divided between patients with hemimandibular hyperplasia (HH, n=8) and hemimandibular elongation (HE, n=18). Using cross-sectional computed tomography images, the thickness of cancelleous bone in the buccal area of the mandible, thickness of buccal cortex in the buccal aspect of the mandible, thickness of cancellous bone in the inferior aspect of the mandible, thickness of buccal cortex in the inferior aspect of the mandible, and cross-sectional surface area of the mandible were measured. Results: In the asymmetry group, the cross-sectional area of the mandible including the inferior alveolar nerve positioned on the affected side was significantly different from the symmetry group. Thickness of cancelleous bone in the buccal aspect of the mandible, thickness of cancelleous bone in the inferior aspect of the mandible, and cross-sectional surface area of the mandible in the affected site of hemimandibular hyperplasia was significantly smaller than in the symmetry group. Conclusion: The inferior alveolar nerve runs lower and in a more buccal direction and shows a smaller cross-sectional surface of the mandible in the hemimandibular hyperplasia patients with asymmetry.

• Archives of Plastic Surgery
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• v.35 no.2
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• pp.152-158
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• 2008

Purpose: Mandibulotomy approach and mandible sparing approach are most common methods for oropharyngeal cancer surgery. Good surgical view and convenience of flap inset are advantages of mandibulotomy approach but deformity of mandible contour, postoperative malocclusion and radionecrosis are its limitations. To make up for the limitations, mandible sparing method is commonly performed, but limited surgical view and difficulties of flap inset are the weak points of this approach. The purpose of the study is to compare mandibulotomy and mandible sparing approaches in postoperative complications and progression of the treatment in oropharyngeal cancer operation and reconstruction. Methods: Single reconstructive microsurgeon operated for oropharyngeal cancer patients with different surgeons of head and neck department who prefer mandibulotomy and mandible sparing approach respectively, and we compared the frequency of postoperative complication, operation time, duration of hospitalization and recurrence rate between two different surgical approaches. Results: Mandibulotomy approach was used in 18 patients and mandible sparing approach was used in 15 patients. In mandibulotomy approach, there happened one case of teeth injury and one case of necrosis of skin and gingiva, but there happened no malocclusion and radionecrosis. In mandible sparing approach, there were 3 cases of fistula and 2 cases of infection which are significantly higher than mandibulotomy approach. There were no significant differences between early regional recurrence and duration of hospitalization. Conclusion: In this study we compared two different methods for the surgical approach in oropharyngeal cancer surgery. As mandible sparing approach has difficulties of limited surgical view, it can be used for the limited indications of anterior tongue and mouth floor cancer. Mandibulotomy approach has advantages of good surgical view and convenience of flap inset. In this method preservation of gingival tissue, watertight fashion suture, delicate osteotomy and plate fixation to maintain occlusion are the key points for the successful results.