• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.2
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• pp.113-118
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• 2002

Conventional radiograph, computed tomograph (CT), magnetic resonance image (MRI) are commonly used methods for diagnosis of oro-maxillofacial cancer. MRI is an effective tool to verify soft tissue lesion however, metal produces black artifacts in the image. Therefore, metal structure should be removed before taking MRI to diagnose head and neck cancer patients. A 52-year-old female patient with adenocarcinoma in the posterior right soft palate was referred to take a MRI before surgery. She has 7-unit porcelain fused to metal bridge in the maxilla. Eight-unit Tagis-Vectris fixed partial denture was fabricated to replace her existing PFM bridge to take a MRI without any artifact before and after surgery. The patient satisfied with her restorations in terms of esthetics, function after 11 months. Even though minor staining was detected, Tagis-Vectris restoration fixed partial denture was intact during observation period.

• Journal of Oral Medicine and Pain
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• v.33 no.4
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• pp.395-399
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• 2008

Orofacial pain and limited range of mouth opening as symptoms of temporomandibular disorder are mainly triggered by the structural and/or functional changes of temporomandibular joint and related structure itself. But careful diagnostic evaluation should be needed because they may be occurred by another pathologic conditions such as neoplasm in head and neck region. If there would be atypical pain characteristics or clinical features, systemic comorbid symptoms, or poor response to treatment, advanced imaging modalities such as CT or MRI will be mandatory for differential diagnosis. We experienced the case which was diagnosed as nasopharyngeal cancer mimicking temporomandibular disorder, and reviewed clinical considerations for proper differential diagnosis.

• Journal of Oral Medicine and Pain
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• v.25 no.3
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• pp.293-303
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• 2000

앵글씨 분류에 따른 최대개구시 하악의 수직 변위에 대한 차이를 확인하고, 수직 하악운동에 영향을 주는 골격요소를 확인하기 위하여, 측두하악관절 및 저작계 이상에 대한 증상 및 병력이 없으며 발치 및 교정치료의 경험이 없는 광주지역 대학에 재학중인 학생들을 대상으로, 앵글씨 구치부 관계에 근거하여 1급군(남:30명, 여:49명), 2급군(남:18명, 여:24명)과 3급군(남:18명, 여:33명)으로 분류하여 총 172명(연령 범주:20-30세)의 학생을 선택하였다. 전남대학교 병원 구강내과에서 사용하는 계측용자를 이용하여 최대 개구시 상하악 중절치 절단면간의 거리를 측정하였다. 대상자들의 진단모형을 만들어 상하악궁 길이와 폭경를 측정하였다. 대상자들에 대한 두부 규격방사선 사진을 촬영, 작도하고 방사선학적 지표를 계측, 비교분석하였다. 앵글씨 분류 1급군, 2급군 그리고 3급군 절치간 최대개구량은 3급군이 가장 컸으며 모든 군에서 남자가 여자보다 컸다. 구치간 최대개구량은 앵글씨 분류 1급군, 2급군 그리고 3급군에서 각 군간의 유의한 차이는 없었으나, 모든 군에서 남자가 더 컸다. 앵글씨 분류 1급군과 2급군의 하악운동에서 총 하악골 길이, 하악지 길이, 하악 하연부 길이 그리고 상악궁 폭경이 변수로 나타났으며, 상하악궁 길이와는 역상관관계를 나타내었다. 앵글씨 분류 3급군의 하악운동에서 상하악궁 길이와 안면 부길이가 1급군과 2급군과는 다른 중요한 변수로 나타났으며, 상악궁의 폭경과는 역상관관계를 나타내었다. 이상의 결과로 보아 앵글씨 분류 각 군에서 하악개구운동은 안면 골격구조의 영향을 받으며, 각 군간에 영향을 주는 안면 골격 요소들은 차이가 있었다. 따라서 이러한 골격적 요소들은 개구량 개선을 위한 진단과 치료시 고려되어야 할 것으로 사료된다.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.1
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• pp.35-46
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• 2023

Congenitally missing teeth are one of the most prevalent dental anomalies in the oral cavity. In this study, the prevalence, distribution, and symmetry of congenitally missing permanent teeth among 1,865 patients aged 7 to 15 years who visited the Pediatric Dentistry Department of Wonju Severance Christian Hospital from March 2011 to May 2021 and took panoramic radiographs were investigated and analyzed. Most of the patients had one or two congenitally missing teeth, mainly in the second premolars and lateral incisors. Congenitally missing teeth occurred more in the mandible than in the maxilla, and there was no significant difference in prevalence between the left and right sides. Congenitally missing teeth tend to occur symmetrically on the left and right sides and in the maxilla and mandible, depending on the tooth. Early oral examination and radiological examination are required to prevent complications due to congenitally missing teeth, and appropriate interdisciplinary treatment is required.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.3
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• pp.317-326
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• 2011

The mental foramen and anterior loop of the mandibular canal are important landmarks for mandibular surgical procedures. The purpose of this study was to analyze the shape and position of the mental foramen and anterior loop of the mandibular canal on the computed tomography (CT) images, and apply the results clinically. CT images of 96 patients (33 male, 36 female, age range 17~43 years, mean $24.6{\pm}4.99$ years) were enrolled. The horizontal and vertical position of the mental foramen, as well as the distance from the root apices were measured. The distance of the anterior loop of the mandibular canal to the root apices, and the buccal angle were measured. The mental foramen was found mostly below the second premolar observed in 81 cases (46.0%), between the first and second premolars in 67 cases (38.0%), and between the second premolar and first molar in 19 cases (10.2%). The mean distance between the mental foramen and the lower border of the mandible was $12.20{\pm}1.77$ mm, the mean distance between the mental foramen and root apex was $5.16{\pm}0.98$ mm. The mean distance of the anterior loop of the mandibular canal was $5.80{\pm}2.00$ mm. The buccal angle measured at $47.7{\pm}9.07^{\circ}$. The distance between the root apex and mental foramen measured as $5.16{\pm}0.98$ mm on panoramic radiography, and $6.2{\pm}3.07$ mm on CT. The mean distance between the mental foramen and mandibular canal was $5.39{\pm}1.62$ mm. When performing surgical procedures such as installing dental implants, it is important to minimize surgical trauma, especially the risk of damage to the mental nerve. To optimize the surgical outcome, a careful assessment of the shape and position of the mental foramen and the anterior loop of the mandibular canal must be made. CT images are useful for finding such anatomic structures.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.324-332
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• 2011

Purpose: The purpose of this study was to compare the stress distribution of teeth and jaw on load by differentiating property of materials according to each layer of widely used mouthguard. Materials and methods: A Korean adult having normal cranium and mandible was selected to examine. A customized mouthguard was constructed by use of DRUFOMAT plate and DRUFOMAT-TE/-SQ of Dreve Co. according to Signature Mouthguard system. The cranium was scanned by means of computed tomography with 1mm interval. It was modeled with CANTIBio BIONIX/Body Builder program and simulated and interpreted using Alter HyperMesh program. The mouthguard was classified as follows according to the layers. (1) soft guard (Bioplast)(SG) (2) hard guard (Duran)(HG) (3) medium guard (Drufomat)(MG) (4) soft layer + hard layer (SG + HG) (5) hard layer + soft layer (HG + SG) (6) soft layer + hard layer + soft layer (SG + HG + SG) (7) hard layer + soft layer + hard layer (HG + SG + HG) The impact locations on mandible were gnathion, the center of inferior border, and the anterior edge of gonial angle. And the impact directions were oblique ($45^{\circ}$). The impact load was 800 N for 0.1 sec. The stress distribution was measured at maxillary teeth, TMJ and maxilla. The statistics were conducted using Repeated ANOVA and in case of difference, Duncan test was used as post analysis. Results: In teeth and maxilla, the mouthguard contacting soft layer of mandibular teeth presented lowest stress measure and, in contrast, in condyle, the mouthguard contacting hard layer of mandibular teeth presented lowest stress measure. Conclusion: For all impact directions, soft layer + hard layer + soft layer, the mouthguard with three layers which the hard layer is sandwiched between two soft layers, showed relatively even distribution of stress in impact.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.3
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• pp.301-307
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• 2012

50-year-old female and 50-year-old male were referred to the department of the oral and maxillofacial surgery of Kyungpook national university dental hospital with asymptomatic lesions on their posterior mandibular body areas. They were discovered incidentally on panoramic radiographs during routine dental examination. Physical examination revealed no remarkable findings. Each panoramic radiograph showed well defined radiolucent lesions without hyperostotic border on their posterior mandibular body area. At first they were diagnosed as benign tumors because they looked like multilocular pattern and one of the patient showed discontinuity of mandibular canal within the lesion. CT scans demonstrated well demarcated and irregular lingual depression filled with fat tissue and they were diagnosed as developmental salivary gland defects. One of the lesion showed no change on follow-up panoramic radiograph after 4 months. Developmental salivary gland defects resembling benign tumor are atypical cases and it is suggested that confirmatory imaging using CT or MRI should be taken.

• Journal of Oral Medicine and Pain
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• v.38 no.3
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• pp.267-274
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• 2013

This study was performed to investigate the skeletal factors related to open lock of the temporomandibular joint(TMJ). We compared the skeletal measurements on the cephalogram and transcranial radiograph among 3 groups, open lock group consisting of consecutively filed 50 patients with at least one open lock episode within recent 1 year, temporomandibular disorder(TMD) group of 50 TMD patients without open lock diagnosed by Research Diagnostic Criteria for TMD (RDC/TMD) Axis I, and normal group of 50 patients without TMD or open lock. The patients of TMD and normal group were randomly selected in an age-and-gender-matched way with ones of open lock group. Open lock group showed smaller saddle angle than normal group on cephalograms and steeper inclination of the articular eminence than TMD and normal groups on transcranial radiographs. These results imply that the patients with the joint located more anterior and the articular eminence with steeper inclination might be riskier to TMJ open lock.

• Journal of Oral Medicine and Pain
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• v.34 no.3
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• pp.247-256
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• 2009

The purpose of this study was to investigate the changes of the pharyngeal space when the following appliances were inserted: the mandibular advancement appliance (MAA), tongue retaining appliance (TRA), and mandibular advancement-tongue retaining appliance (MATRA). Nine male dental students exhibiting Class I occlusion, normal body mass index (BMI), and no signs and symptoms of snoring were selected for this study. The three kinds of snoring appliances (MAA, TRA and MATRA) were fabricated for each subject. The mandibular advancement of the MAA and MATRA was set at a distance of 5 mm, and the TRA and MATRA were made to hold the tongue in front of the maxillary incisors by 10 to 20 mm. Lateral cephalometric radiographs of the following four states - with no appliance, MAA, TRA, and MATRA - were taken to examine any anatomical changes resulting from the application of the appliances. All four radiographs were traced and analyzed for twenty selected variables related to the pharyngeal space, cranio-cervical posture, and position of the soft palate and hyoid bone. According to the results of this study, there were significant increases in both the upper and lower oropharyngeal spaces when the mandible and tongue were protruded simultaneously, although there was a significant increase only in upper oropharyngeal space when the mandible or tongue was advanced separately. In conclusion, it is suggested that the MATRA may result in more positive effect on the control of snoring and OSA compared to a single use of the MAA or TRA, especially for the patients whose upper airway obstruction occurs in the lower oropharynx.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.2
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• pp.151-156
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• 2006

Purpose : The aim of this study was to determine the accuracy of clinical and radiologic assessments in detecting positive cervical lymph nodes in oral cancer. Materials and Methods : We had reviewed the preoperative clinical, radiologic and postoperative histopathologic reports of 46 patients who had been diagnosed as oral cancer and underwent surgical excision combined with neck dissection (52 sides of neck) in the Department of Oral and Maxillofacial Surgery, College of Dentistry, Yonsei University from the July 1, 1992 to the April 30, 1999. Results : The results were as follows 1. The male to female ratio was 4.38 : 1 and the mean age was 57. 2. Sensitivity values for the preoperative assessment of cervical lymph node metastasis in oral cancer were 62.5 % in clinical examination and 50.0 % in radiologic assessments. Specificity values were 77.8 % in clinical examination and 94.4 % in radiologic assessments. 3. False positive values were 44.4 % in clinical examination and 20.0 % in radiologic assessments. False negative values were 17.6 % in clinical and 19.0% in radiologic assessments. 4. Overall efficiency values were 73.1 % in clinical examination and 80.8 % in radiologic assessments. Summary : There were some limits on the accuracy of clinical and radiologic assessments in the preoperative detection of the cervical lymph nodes in oral cancer. To improve the accuracy, it is important to communicate between clinician and radiologist, and adjunctive diagnostic measures, ultrasound and fine needle aspiration cytology, were helpful increasing the overall efficiency. In the high risk sites (oral tongue and floor of the mouth) the false negative value is higher and the overall efficiency in radiologic evaluation is lower than those of the low risk sites (gingiva and alveolar ridge, retromolar trigone and buccal mucosa ). The elective neck dissection should be considered in the high risk sites.