• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.175-182
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• 1990

This study was performed to investigate the influence of occlusal change on the masticatory muscle activity. 8 students without any symptom of T.M.J. dysfunction, any history of prosthodontic or orthodontic treatment on dental college of WonKwang Univ. were participated in this study. The activity of masseter and anterior temporal muscles were measured by bioelectric processor(EM2, Myotronics, Inc., U.S.A.) during voluntary maximal clenching on natural teeth, by splint with bilateral posterior surface contact, by splint with unilateral posterior surface contact, and by splint without unilateral posterior teeth contact. The obtained results were as follows ; 1. The loss of posterior contact on noe side resulted in change of the activity of anterior temporal and masseter muscle during clenching on ipsilateral side, but there was no change of muscle activity on contralateral side. 2. The activity of anterior temporal and masseter muscle during clenching were not affected by the pattern of occlusal contact. 3. There were no difference between the activity of anterior temporal and masseter miuscle during clenching by natural teeth and by occlusal splint.

• The Journal of the Korean dental association
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• v.21 no.4 s.167
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• pp.293-297
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• 1983

Bruxism이란, 일반적으로 기능이외의 목적으로 상하악 치아를 악물거나 갈음질 하는 것이라고 정의된다. 동일한 상태를 서술하는 용어로 neuralgia traumatica, Karolyi effect, occlusal habit neurosis, parafunction 등이 있으며, 수면중의 이갈음질을 bruxism, 주간의 습관성 이갈음질을 bruxomania로 구분하기로 한다. 또한 centric bruxism과 eccentric bruxism으로 분류하기도 한다. eccentric bruxism은 통상적 의미의 수면중의 bruxism이며, 하악의 측방운동중의 이갈음질이고 뽀드득하는 갈음질 소리를 냄, 저작근육의 긴장도가 증가되어 있으면서 등장성수축을 나타내고, 비중심위의(eccentric) 교합간섭이 주요 유발인자인 반면에 centric bruxism은 중심교합위에서 상하악 치아를 간헐적으로 악무는 것(clenching)은 의미하고 - 지속적으로 악무고 있는 것은 clamping이라고 함.- 주로 주간에 행하며 갈음질소리를 들을 수 없고, 역시 저자근육의 긴장도가 증가되어 있으며 등률성수축을 나타내고, 중심교합위에 근접하여 존재하는 교두간섭이 유발인자이다. bruxism이나 clenching과 부정교합의 관계는 bruxism과 clenching은 부정교합을 야기할 수 있고, 부정교합도 역시 bruxism과 clenching을 유발시키는 작용을 할 수 있는 악순환적 관계이다. 현저한 부정교합을 가지고 있는 bruxism환자의 교정치료는 그 목적이 bruxism의 치료라기보다는 오히려 부정교합의 치료이며 부차적으로 bruxism의 치료를 기대하게 된다. 그러나 bruxism이 장기간 지속되어 치아 및 그 주위조직, 악관절과 신경근계에 심한 손상을 주었을때의 교정치료는 일반적으로 제한을 받을 뿐만아니라 bruxism의 처치에는 거의 무의미한 치료가 될 수 있다. 따라서 거자는 bruxism 환자의 교정치료라는 제목의 원고 청탁을 받았으나 편집위원의 양해아래 장치를 이용한 bruxism의 치료에 관하여 서술하려 한다.

• The korean journal of orthodontics
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• v.42 no.4
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• pp.159-168
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• 2012

Objective: The aims of this study were to investigate mandibular deformation under clenching and to estimate its effect on the stability of orthodontic mini-implants (OMI). Methods: Three finite element models were constructed using computed tomography (CT) images of 3 adults with different mandibular plane angles (A, low; B, average; and C, high). An OMI was placed between #45 and #46 in each model. Mandibular deformation under premolar and molar clenching was simulated. Comparisons were made between peri-orthodontic mini-implant compressive strain (POMI-CSTN) under clenching and orthodontic traction forces (150 g and 200 g). Results: Three models with different mandibular plane angles demonstrated different functional deformation characteristics. The compressive strains around the OMI were distributed mesiodistally rather than occlusogingivally. In model A, the maximum POMI-CSTN under clenching was observed at the mesial aspect of #46 (1,401.75 microstrain [${\mu}E$]), and similar maximum POMI-CSTN was observed under a traction force of 150 g (1,415 ${\mu}E$). Conclusions: The maximum POMI-CSTN developed by clenching failed to exceed the normally allowed compressive cortical bone strains; however, additional orthodontic traction force to the OMI may increase POMI-CSTN to compromise OMI stability.

• Journal of Oral Medicine and Pain
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• v.40 no.3
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• pp.102-109
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• 2015

Purpose: The purpose of this study was to assess the association between sleep disturbances and personality type. Methods: Five hundred twenty-four college students in Gyeonggi-do completed the Myers-Briggs Type Indicator (MBTI) and a questionnaire and collected data were analyzed by SAS 9.4 program. Results: Extroversion (E) type, sensation (S) type, and perceiving (P) type had significantly higher prevalence of insomnia than introversion (I) type (p<0.05), intuition (N) type (p<0.05), and judging (J) type (p<0.001), respectively. Tooth grinding, snoring and insomnia appeared to occur more frequently in feeling (F) type than in thinking (T) type. Tooth clenching, tooth grinding and snoring seemed to occur more frequently in S type than in N type. Insomnia occurred significantly the most frequently in sensation-feeling (SF) type (p<0.05). Tooth grinding and snoring seemed to occur the most frequently in SF type. A significantly increased percentage of sensation-perceiving (SP) type demonstrated insomnia (p<0.001). Tooth clenching, tooth grinding and snoring seemed to occur the most frequently in sensation-judging (SJ) type. Sensitive or nervous type of personality had significantly higher prevalence of insomnia than relaxed or general type of personality (p<0.01). A significantly increased percentage of subjects with bad general health status showed insomnia (p<0.0001). Tooth clenching and snoring seemed to occur the most frequently in subjects with bad general health status. A significantly decreased percentage of normal weight subjects demonstrated tooth grinding (p<0.05). Snoring occurred significantly the most frequently in overweight subjects (p<0.001). Tooth clenching showed significant correlation with stress (p<0.01) and personality (p<0.05). Snoring showed significant correlation with stress (p<0.05) and body weight (p<0.001). Insomnia showed significant correlation with stress (p<0.0001), personality (p<0.01), and general health status (p<0.0001). Conclusions: Sleep disturbances including tooth clenching and insomnia were associated with personality type and it is desirable to manage them considering personality type.

• Journal of the HCI Society of Korea
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• v.1 no.2
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• pp.9-17
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• 2006

We propose an EMG-based input interface technology for helping the tetraplegic to utilize mouse, keyboard and power wheelchair. Among possible actions for the tetraplegic utilizing these devices, teeth-clenching is chosen as an input action. By clenching left, right or both teeth, and controlling the clenching duration, several input commands for utilizing the devices can be conducted. EMG signals generated by teeth-clenching are acquired around one's left and right temples and they are used as control sources for utilizing the devices. We develop signal acquisition devices, signal processing algorithms, and prototype systems such as power wheelchair control, mouse control, and game control. Our experimental results with the tetraplegic show that the proposed method is useful for utilizing the devices.

• Sleep Medicine and Psychophysiology
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• v.12 no.1
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• pp.23-26
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• 2005

Bruxism is defined as 'diurnal or nocturnal parafunctional activity including clenching, bracing, gnashing, and grinding of the teeth'. Bruxism and clenching are two of the most common contributing factors in patients with temporomandibular disorders and craniofacial pain disorders. Even though many studies report the high prevalence of bruxism, its cause is still not clear. Occlusal interference has been regarded as a major etiologic factor. Nowadays, psychological stress and sleeping disorders are generally regarded as major possible etiologic factors. More than likely, the cause is multifactoral and overlapping, which makes it difficult for the practitioner to apply comprehensive and effective management strategies. Although dentists and psychologists generally believe that effective treatment is best achieved with a better understanding of the etiology of a given disorder, for now treatment for this type of disorder must proceed without a clear understanding of etiology. To overcome this obstacle, evidence-based comprehensive management protocols based on accumulated scientific findings should be provided. In this presentation, epidemiology, etiology, and the characteristics of bruxism are reviewed. Diagnostic procedures and management strategies focused on occlusal appliances and behavioral approaches are also discussed.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.405-417
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• 2010

Previous studies have already shown that mouthguard is effective in protecting jaw bone, teeth and oral tissue against sports trauma. However, other than severe trauma, repetitive force, such as disorders like clenching, cause teeth or oral tissue damage. These kinds of disorders usually present pathologic attrition in the posterior teeth, resorption in alveolar bone, loss of teeth and destruction of occlusion. Wearing a mouthguard is believed to be effective in preventing these disorders. But its effect is not examined thoroughly enough. The purpose of this study is to identify whether mouthguard is effective in reducing strain caused by clenching. Mandibular first molars in the normal occlusal relationship without any history of dental treatment were chosen. Biaxial type strain gauge was placed on the buccal surface of the tooth. Having maximum occlusal force, measured by load cell, as a standard, clenching intensity were divided into three stages; moment of slightly tooth contact, medium bite force (50% of maximum bite force), maximum bite force. Strain occurring in dentition in each stage with and without mouthguard was measured. Changes in strain (on dentition) between each stage and difference in strain, between with or without mouthguard were recorded by PCD-300 analyzer and PCD-30 soft ware. The data was statistically analyzed by Wilcoxon signed rank test. The following results were drawn; Without mouthguard, strain given on dentition increased as the clenching force increased. With mouthguard, strain given on dentition also increased as the clenching force increased. With mouthguard, strain decreased, in all cases of clenching force stages. Data on the moment of slightly tooth contact stage, had no statistical significance. However, with mouthguard, 50-90% of decrease in strain could be obtained in maximum occlusal force, compared to the group without mouthguard. Mouthguard decreased the strain on the dentition, caused by clenching. Therefore, mouthguard seems to be effective in preventing damage on dentition, by acting against clenching, which occurs both consciously and unconsciously during sports activities.

• The korean journal of orthodontics
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• v.26 no.1 s.54
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• pp.65-82
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• 1996

This study was carried out to study the changing patterns in muscle activities in Angle's II and Class III malocclusion patients following activator therapy, To study the activities of anterior temporal(T.A.), masseter(M.M.), posterior temporal(T.P.), and anterior belly of digastric(D.A.) muscles, surface electrodes were placed on 15 Angle's Class II and 17 Angle's Class III malocclusion patients and following conclusions were obtained after electromyographic recordings were taken at prior to the activator therapy and at some time between 6 -12 month after the start of activator therapy. 1. Class II and Class III malocclusion groups, when compared to normal occlusiongroup, showed no significant differences during resting and swallowing. But significant differences were observed in masseter and posterior temporal muscles during clenching. 2. Most of the muscles studied showed a certain pattern, that is those groups whose pre-treatment E.M.G. were lower than the normal value showed significant increase after activator therapy, whereas those groups whose pre-treatment E.M.G. were higher than the normal value showed significant decrease after activator therapy. This pattern was observed in all of the muscle groups studied except T.A.(swallowing), T.P.(clenching) and D.A.(swallowing, clenching) in Angle's Class III malocclusion group and in Angle's Class II malocclusion group, above tendency were observed only in T.A.(swallowing), M.M.(resting, swallowing) and T.P.(clenching). This pattern was less obvious during clenching. 3. When E.M.G. activity after activator therapy between Angle's Class II and Class III malocclusion group was compared, Class III malocclusion group showed more increase during resting, and Class II malocclusion group showed more increase during swallowing and clenching excepting M.M. and D.A. respectively.

• Journal of Oral Medicine and Pain
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• v.13 no.1
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• pp.23-33
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• 1988

The purpose of this study was to standardized and classify the coordination pattern among the chewing side and non-chewing side masseter and anterior muscles, in terms of EMG values on lateral excursion, clenching, and mastication in presence of the non-chewing side. In this study, 25 subjects were selected for experiment of lateral excursion, clenching and mastication and EMG value of the masseter and anterior temporal muscle on both sides were recored 2 times respectively. The bioelectric processor model EM2(Myo-tonic research, INC. U.S.A.) with the surface electrodes were used to record the EMG activity during all experimental procedures. The results were as follows : 1. During lateral excursion on intereference of non-chewing side, the EMG values of the temporal muscle were significantly more prominent than those of the temporal muscle on the non-chewing side. The EMG values of non-chewing side were significantly more prominent than those of chewing side on the both side masseter muscle and those of chewing side were significantly more prominent than those of non-chewing side on the both side temporal muscle. 2. During clenching on the occlusal interferance, the EMG values of non-chewing side masseter muscle were most prominent. 3. During mastication on the occlusal interferance, the EMG values of the chewing side temporal muscle were most prominent and those of non-chewing side temporal muscle were the lowest. 4. The EMG values of temporal muscle of non-chewing side on interferance were significantly more prominent than those of canine guidance during lateral excursion. 5. During clenching on the occlusal interferance, the EMG values of the masseter and the temporal muscles of the non-chewing side were significantly more prominent than canine guidance, but those of chewing side temporal muscle on canine guidance were significantly more prominent than those of interferance. 6. During mastication on canine guidance, the EMG Values of the temporal muscle on the chewing side, the masseter muscle on the chewing side and the temporal muscle on the non-chewing side were more prominent than those of interferance, but temporal muscle of non-chewing side was not different between canine guidance and occlusal interferance on non-chewing side.

• Restorative Dentistry and Endodontics
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• v.35 no.1
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• pp.20-23
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• 2010

Mouthguards were used to protect boxers from lip lacerations and other soft tissue injuries in the late 19th century. Now they are used various parts of dental treatment, which are sports protective aid, bleaching tray, orthodontic retainer, implant insertion guide tray, splint and so on. Repeated dislodgement of Class V restoration due to habitual clenching stress should be restored with stress control. Mouthguard can be used as stress relief device. This case describes methods that can relieve occlusal force to teeth by using mouthguard. Satisfactory results can be obtained by using mouthguard for retention of repeated dislodgement Class V restorations. If patients suffered from repeated restorations of Class V due to clenching, mouthguard can be used additional device to relieve the occlusal stress in conservative dentistry.