• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.2
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• pp.256-261
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• 2005

Scleroderma is a connective tissue disease of unknown etiology, but known as a kind of auto-immune disease. It is most common in women especially in $30{\sim}50$ years, and very rare in childhood. It can be classified into two main classes : localized scleroderma & systemic sclerosis. Localized type has better prognosis, and usually involves skin only, or in some cases, the muscle below, except inner organs. Systemic type involves skin, oral mucosa and major internal organs. Involving facial skin, we can see small and sharp nose, expressionless stare and narrow oral aperture. Usually they have Raynaud's phenomenon, and in progress, show mouth opening limitation and sclerosis of tongue and gingiva. It is called CREST syndrome showing calcinosis cutis, Raynaud's phenomenon, esophageal dysfunction, sclerodactyly, and telangioectasia. Treatment of scleroderma is systemic and localized steroid therapy, use of collagen-link inhibitor (D-penicillamine), immune depressor and etc. Mouth opening limitation can be improved by mouth stretching exercise. We report a 6 years old boy, diagnosed with localized scleroderma who had mouth opening limitation. We could get additional mouth opening, and have done successful restorative treatment of mandibular and maxillary 1st and 2nd deciduous molar under deep sedation with nitrous oxide and enflurane.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.1
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• pp.100-106
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• 1993

This paper aims to synthesize the research on fatigue fracture mechanisms of high strength aluminum alloys which are widely used in motorcars or airplanes to prevent accidents. To measure the data of crack opening ratio, the same materials and method are used for evaluating the fatigue crack propagation rate as an effective stress intensity factor. But, many researchers have brought different results. An exact crack opening ratio was, therefore, proposed for getting a more accurate fatigue crack propagation rate. The main conclusions obtained are as follows. (1) As a result of the fatigue test, the value of the crack opening ratio is the same regardless of the stress ratio. (2) The value of crack opening ratio is different according to the measuring point. After measuring the crack propagation rate by using an effective stress intensity factor, the crack opening ratio value measured at the crack mouth by a clip gage, or measured rear of the specimen by a strain gage is more accurate than that by any other measuring test.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.849-855
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• 2000

This study evaluated the effect of restraint of pressure induced bending(PIB) on crack mouth opening displacement(CMOD) for circumferential through-wall crack in pipe by using both elastic and elastic-plastic finite element analyses. The analyses results showed the restraint of PIB was decreased crack opening for a given crack length and tensile stress, and the effect was considerable for large crack and short restraint length. Also, the restraint effect on CMOD was independent on the variation in pipe diameter and decreased with increasing pipe thickness, and it depended on not total restraint length but short restraint length for non-symmetrically restrained. Additionally, the effect of restraint of PIB was more significant in the elastic-plastic analysis results compared with in the elastic analysis results.

• Journal of Oral Medicine and Pain
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• v.22 no.1
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• pp.7-13
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• 1997

In order to evaluate the outcome of conservative treatment for acute or chronic closed lock, 127 patients were subjected at the Dept. of Oral Medicine, PNUH, from 1991. All the symptoms were analyzed and the results according to treatment modalities were compared before and after treatment. 1. Closed lock patients were more often seen in women of twenty and thirty. 2. The most common reasons for treatment were functional pain, limitation of mouth opening, restricted laterotrusion to non-effected side, deflection on opening but, on the contrary, noise was the least. 3. Most of closed lock patients were curedin six months. 4. Conservative treatment including stabilization splint produced better results. 5. Functional pain and limitation of mouth opening were relieved and maximumm comfortable opening was expanded, but joint noise decreased in the chronic and increased in the acute.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.4
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• pp.271-282
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• 2021

This study aims to understand the opening efficiency of the finless porpoise escape guide net by the type of extension net that is the part to which the escape guide net is attached in stow net. To this end, extension nets were manufactured in full size and the net mouth area and towing tension were investigated according to the towing speed (0.2, 0.4, 0.6 and 0.8 m/s) and the type of extension net (25 mm net and raschel net) in the water tank. As a result, the net mouth area of the guide net was larger when the raschel net was used for the extension net than when the 25 mm net was used under all towing speeds. In addition, regardless of the type of extension net, the net mouth area reached about 80% of the maximum value at a towing speed of 0.4 m/s. In the field, fishing operation of stow net is performed only when the current speed is above 0.4 m/s. Therefore, the speed of 0.4 m/s was confirmed as a meaningful value to determine whether it is possible to operate. As a result of analyzing the relationship between the net mouth area of the guide net and the towing tension, it was confirmed that the difference in the net mouth area of the guide net according to the type of the extension net was due to the difference in the solidity ratio.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.4
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• pp.322-328
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• 1993

The trauma has been known as a major etiologic factor in temporomadibular joint disorders. The endotracheal intubation is suspected as one of the traumatic factor to temporomandibular disorder. But there are few reports about the amount of mouth opening during endotracheal intubation and temporomandibular joint disorder after endotracheal intubation. The authors studied the effects of endotracheal intubation to temporomandibular joint with 70 patients given surgical operation through general anesthesia. The results were as follows. 1. The mean amount of mouth opening for entire patients during endotracheal intubation was 26.3mm (s, d : 2.6), for oral intubation group 25.9mm(s, d : 3.2), for nasal intubation group 26.6mm(s, d : 1.9). There was no difference between two group stastically. (p<0.05) 2. 1 week later endotracheal intubation, the maximum mouth opening increased 1.5mm for entire patients, 1.5mm for oral intubation group, 1.6mm for nasal intubation group than behare endotracheal intubation. 3. Five patients complained the discomforts around temporomandibular joint after endotracheal intubation. The amount of mouth opening during endotracheal intubation was within physiologic range. It seemed that $45^{\circ}$ upward endoscopic lifting for exposure of glottis gave trauma to temporomandibular joint.

• Imaging Science in Dentistry
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• v.47 no.4
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• pp.219-226
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• 2017

Purpose: This study investigated the relationship between pain and internal derangement in temporomandibular disorder(TMD) patients using magnetic resonance imaging (MRI). Materials and Methods: This study analyzed 356 TMD patients (712 temporomandibular joints [TMJs]). The inclusion criteria were the presence of spontaneous or provoked pain on one or both TMJs and having undergone MRI. The patients with provoked pain were divided into 3 groups: pain on palpation, pain on mouth opening, and pain on mastication. MRI was performed using a 1.5-T scanner. T1- and T2-weighted parasagittal and paracoronal images were obtained. According to the findings on the T1-weighted images, another 3 groups were created based on internal derangement: normal, disc displacement with reduction, and disc displacement without reduction. The MRI findings were independently interpreted by 2 experienced oral and maxillofacial radiologists at 2 different times. Statistical analysis was performed by the chi-square test using SPSS (version 12.0; SPSS Inc., Chicago, IL, USA). Results: Provoked pain on mouth opening was found to be correlated with internal derangement in TMD patients (P<.05). However, spontaneous pain and provoked pain on palpation or mastication were not associated with internal derangement(P>.05). Conclusion: These results suggest that internal derangement was a significant predictor of provoked pain on mouth opening.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.3
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• pp.125-132
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• 2015

Objectives: The purpose of this study was to clarify which findings in magnetic resonance imaging (MRI) are good predicators of pain and mouth opening limitation in patients with temporomandibular joint (TMJ) internal derangement (ID). Materials and Methods: Clinical examinations for pain and mouth opening limitation were conducted for suspected TMJ ID. MRI scans were taken within a week of clinical examinations. On the oblique-sagittal plane image, readings were obtained in terms of the functional aspect of disc position, degree of displacement, disc deformity, joint effusion, and osteoarthrosis. Multiple logistic regression analyses were conducted to identify the predictors of pain and mouth opening limitation. Results: A total of 48 patients (96 TMJs) were studied, including 39 female patients and 9 male patients whose ages ranged from 10 to 65 years. The resultant data showed significant correlations between pain and the MR imaging of the degree of disc displacement (P<0.05). The probability of there being pain in moderate to significant cases was 9.69 times higher than in normal cases. No significant correlation was found between mouth opening limitation and MRI findings. Conclusion: We identified a significant correlation between clinical symptoms and MRI findings of ID. The degree of anterior disc displacement may be useful for predicting pain in patients with TMJ ID.

• Journal of Oral Medicine and Pain
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• v.22 no.1
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• pp.95-109
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• 1997

The purpose of this research is to investigate the influence on mandibular movements and TMJ sounds with changes of head and neck posture. For the research, twenty patients who had complained of TMJ sounds without any other symptoms of cranio-mandibular disorders, were selected as subjects for measurements of TMJ sounds, and radiographs on transcranial view of TMJ were taken on ten of the subjects. From NHP, UHP, DHP and FHP, aspects of mandibular movement and TMJ sound were investigated from each posture. Aspects of mandibular movement and TMJ sound were observed by measuring total vibration energy(Integral), peak amplitude, maximum amound of mouth opening, and TMJ sound-emitting point using Sonopak for windows (version 1.33) and Bio-EGN(Bioresearch Inc. WI. U.S.A.). Head and neck movement-measuring instrument, CROM(perfomance attainment Inc. U.S.A.) was to maintain even head posture. Degrees of inclination of UHP and DHP were determined at 30' and distance of FHP was 4cm. The results obtained were as follows. 1. Total vibration energy and peak amplitude of TMJ sounds were decreased more on UHP and on UHP and increased more on DHP and FHP than that on NHP. 2. At the maximum mouth opening, distance of TMJ sound-emitting point were decreased more on UHP and increased more on DHP and FHP than that on NHP. 3. The amounts of the maximum mouth opening were increased more on UHP and decreased more on DHP and FHP than that on NHP. 4. For the changes of the head posture with mouth opening observed in radiograph, condylar head was positioned more lower-anteriorly on UHP, and more upper-posteriorly on DHP and FHP than that on NHP. From the results obtained as above, considering positive influence of the change of head and neck posture, avoiding down-head and forward-head posture, and recommending upper- head posture can prevent the progress of temporomandibular disorder and lead to successful treatment for the patients with temporomandibular joint sounds.

• Journal of Oral Medicine and Pain
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• v.41 no.2
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• pp.35-40
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• 2016

Purpose: This study aimed to investigate the characteristics of the symptoms of temporomandibular disorders (TMD) in Korean children and adolescents using representative samples and questionnaires. Methods: A survey involving the interview of 10-, 12-, and 15-year-old children and adolescents regarding the symptoms of TMD was conducted as a part of the 2010 National Oral Health Surveys. The study population included 18,112 subjects (male, 9,734; female, 8,378). The interview involved three questions related to the symptoms of TMD. The prevalence of symptoms of TMD, correlation of the symptoms with sex and age, and the difference in the number of symptoms according to sex and age were analyzed. Results: Among the symptoms of TMD in children and adolescents, the prevalence of temporomandibular joint (TMJ) sounds during mouth opening was 13.0%, while those of TMJ pain and limitation were 3.1% and 4.3%, respectively. While the prevalence of TMJ sounds during mouth opening did not show any statistically significant difference between the sexes, the rates of prevalence of TMJ pain and limitation of mouth opening in were higher in the female subjects than the male (p<0.05). It was also observed that the older the subjects, the higher the prevalence of TMJ sounds, TMJ pain, and limitation of mouth opening (p<0.05). The number of symptoms of TMD was found to be increased among female subjects as well as the older ones (p<0.05). Conclusions: There are variations in the prevalence of symptoms of TMD among Korean children and adolescents according to sex and age, which is consistent with the results of previous studies. It is necessary to conduct a national cohort study to evaluate the risk factors for TMD in children and adolescents.