• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.2
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• pp.169-178
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• 2010

Objective. This study was conducted to observe the effect on appendage muscle strength according to increase in occlusal vertical dimension. Materials and methods. Ten males with a mean age of 21 were selected. The tested occlusal splints were made at the position of increased occlusal vertical dimension of 2mm,3.5mm and 5mm from the intercuspal position. Before and after wearing occlusal splints, the appendage muscle strength were tested by Cybex II dynamometer (Lumex Inc., Ronkonkoma, NY, USA). Results. Statistical analysis using the paired t-test revealed significant differences for flexion and extension of the hip, pronation of the forearm, internal rotation of the shoulder, external and internal rotation of the knee, and dorsiflexion and plantarflexion of the ankle (p<0.05). Conclusions. As the result of this study, we conclude that when occlusal vertical dimension was increased, most of mean muscular strength values were increased. Especially at the position of 3.5mm increased vertical dimension displayed the highest mean muscular strength value than other positions.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.12 no.1
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• pp.62-71
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• 1990

This study was to evaluate the nature of traumatic injuries on anterior teeth of 530 patients and the prognosis of stabilized cases of 102 patients, including possible 18-follow up cases among them, treated at Dental Hospital, Yonsei Medical Center from Mar. 1983 to Feb. 1988. The obtained results were as follows. 1. The peak of monthly distribution of trauma to the anteriors was June and was the lowest in November. The ratio of male to female was 2.6 : 1. The most common incidence of the trauma to the anteriors was seen in the 3rd decades. The most chiefly involved teeth were central incisors in both upper and lower jaws. The causes of trauma were as followed in descending order by first blows, traffic accidents, falls, slip downs, and sports. The types of traumatic injuries of anterior teeth consisted of periodontal tissue injuries(55.9%), the injuries to the hard dental tissues and pulp(31.3%), and alveolar bone injuries(12.8%). 2. 35.1% stabilized anteriors were treated with root canal therapy. The success rate of stabilization was 95.3%, and 92.3% in replantation of avulsed teeth. 3. External root resorption, internal root resorption with calcification of pulp chamber or root canal, ankylosis of root, and other periapical pathosis were seen in follow-up radiographic findings. 4. Success rate of stabilization of the traumatized anteriors after 3 years showed 71.4% average.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.325-334
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• 2008

Statement of problem & Purpose: The purpose of this study was to investigate the effect of a mouth guard material properties on the skull and brain when they were under impact loads on mandible. Material and methods: Two customized mouth protectors having different material propeerst ieach other were made for a female Korean who had no history of brain trauma, no cerebral diseases, nomal occlusion and natural dentition. The 3D finite element model of human skull and brain scanned by means of computed tomography was constructed. The FEM model of head was composed of 407,825 elements and 82,138 nodes, including skull, brain, maxilla, mandible, articular disc, teeth and mouth guard. The stress concentrations on maxillary teeth, maxilla and skull with two mouth guards were evaluated under oblique impact load of 800N onto mandibular 3 loading points for 0.1sec. And the brain relative displacement was compared in two different mouth guard materials under same condition. Result and Conclusion: The results were as follows; 1. In comparison of von Mises stress on maxillary teeth, a soft mouth guard material had significantly lower stress values on measuring point than a hard mouth protector materials (P < .05). 2. In comparison of von Mises stress on maxilla and skull, A soft mouth protector material had significantly lower stress values on measuring point than a hard mouth protector materials (P < .05). 3. For impact loads on mandible, there were more stress concentrated area on maxilla and skull with hard mouth guard than soft with mouth protector. 4. For impact loads on mandible, brain relative displacement had little relation with mouth guard material properties. In results of this study, soft mouth guard materials were superior to hard mouth guard materials for mandible impact loads for prevention of sports injuries. Although the results of this study were not enough to figure out the roles of needed mouth guard material properties for a human head, we got some knowledge of the pattern about stress concentration and distribution on maxilla and skull for impact loads with soft or hard mouth protector. More studies are needed to substantiate the relationship between the mouth guard materials and sports injuries.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.2
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• pp.247-254
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• 2001

There is a growing tendency for injury and it is essential to know about the epidemiology of the injured teeth for proper and timely treatment. Through empirical data analysis of 120 children who came to pediatric dentistry of Kangnung National University Dental Hospital, this study purposes to give an understanding about the injury and analyzes the frequency by children's sex and age, the number of injured teeth according to the area in the mouth, the types of injury, causes and places of injury, the frequency occurred by month and hour, the position of injured teeth, and the elapse of time. The main findings of this study are summarized as follows: 1. The frequency analysis by sex shows that the rate of boys is more likely to be higher than girls(1.6:1). 2. The frequency analysis by age shows that the ratio of children between aged 2~4 and 8~10 are high. 3. The number of injured teeth is generally one(51.7%). 4. Periodontal tissue injury is the main cause for the primary teeth. In case of permanent teeth, the ratio of hard tissue injury which is much increased than the case of the primary teeth, is similar to that of periodontal tissue injury. 5. The main cause of injury is fall for both dentition; In case of permanent dentition, the ratio of injury by sports is increased. 6. The place of injury for primary teeth is mainly home(38.8%); Street and school for permanent teeth(42.5% and 35%, respectively). 7. The frequency by month shows that the injury is most frequently occurred in July. 8. The frequency analysis by hour shows that injury for primary teeth mostly happens in the morning; in the afternoon for permanent teeth. 9. The position of injured teeth according to the area in the mouth is mainly maxilla anterior in both case of primary and permanent teeth and especially the ratio of central incisors is high, 10. More than half(59.2%) of patients came to the hospital within one day and the seriously injured were likely to come within one day than the slightly injured.

• Journal of Oral Medicine and Pain
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• v.30 no.3
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• pp.337-344
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• 2005

A tactile sensor employs a piezoelectric element to detect contact frequency shifts and thereby measure the stiffness or softness of material such as tissue, which allows the sensor to be used in many fields of research for urology, cardiology, gynecology, sports medicine and caner detection and especially for cosmetics and skin care. In this study, reliability of the tactile sensor system was investigated with its manual application to the muscles susceptible to temporomandibular disorders. Stiffness and elasticity of anterior temporalis, masseter and trapezius muscles were calibrated bilaterally from 5 healthy men with an average of 24.5$\pm$0.94 years. The tactile sensor used in this study had a computer-controlled and motor-driven sensor unit which automatically pressed down on the skin surface over the muscles being measured and retracted, thereby providing the hysteresis curve. The slope of the tangent of the hysteresis curve (${\Delta}f/{\Delta}x$) is defined as stiffness of the muscle being measured and the distance between the two parts of the curve as its elasticity. To determine inter-examiner reliability, all the measurements were performed by the two examiners A and B, respectively and the same examination were repeated with an interval of 2 days for intra-examiner reliability. The results from this study demonstrated high reliability in measuring stiffness and elasticity of anterior temporalis, masseter and upper trapezius muscles using a tactile sensor system. It is suggested that the tactile sensor system can be a highly reproducible and effective instrument for quantitative evaluation of the muscle in head and neck region.

• Journal of Korean Dental Science
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• v.2 no.1
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• pp.31-38
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• 2009

With today's social and cultural personal interactions, greater leisure time and participation in sports activities, and growing traffic volume, the risk of physical trauma has increased markedly. This is a clinical and retrospective study of patients exposed to oral and maxillofacial trauma. We clinically observed 72 patients with trauma in the Department of Oral and Maxillofacial Surgery, Kyunghee University Dental Hospital, from June 2006 through November 2007. The following data was obtained: 1. The male:female ratio of patients having experienced physical trauma was 6.2:1, with most patients in their twenties. 2. Traffic accident (37.5%) was the most common cause of trauma. 3. The highest incidence of fracture occurred to the zygomatic arch(22.1%) among mid-facial fractures and angle(37.5%), symphysis(35.4%) in mandible fractures. 4. Open reduction (88.9%) was the most frequently used form of treatment. Closed reduction was performed on the remaining 11.1% of cases. 5. Teeth and alveolar bone damage occurred in 23.6% of all cases. 6. Other injuries that were related to mid-face fracture occurred in 27.8% of all cases. 7. Post-operative complications occurred in 31.9% of cases, and the highest complication was the nerve injury.

• The Journal of Advanced Prosthodontics
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• v.5 no.4
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• pp.388-395
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• 2013

PURPOSE. The purpose of this study was to estimate the effects of occlusal stability to identify action mechanisms of mouthguards, known to have a modulatory effect on limb muscle function. MATERIALS AND METHODS. This study included 20 male subjects to perform the isokinetic muscle tests and the Wingate anaerobic power test on both knee joints under five closed-mouth conditions: without or with 4 types of mouthguards with thickness of 2 mm based on premolar area: (1) full-coverage, (2) anterior partial-coverage, (3) right posterior partial-coverage, and (4) left posterior partial-coverage. The obtained results were subjected to One-way ANOVA with repeated measures, followed by post hoc test of the contrast method (${\alpha}$=.05). RESULTS. There was no significant difference between the closed position with and without a full-coverage mouthguard in all variables. However, significant differences were observed between with and without a partial-coverage mouthguard in muscular endurance during extension of the left knee, muscular power and endurance during flexion of the right knee. Additionally, significant differences were found between occlusal states with full- and partial-coverage mouthguards in muscular power and endurance during extension of the left knee. CONCLUSION. These findings indicate the elevation of vertical dimension by 2 mm or the inducement of occlusal stability had little effect on isokinetic muscle strength and anaerobic performance, while uneven distribution of occlusal force might have some positive effects.

• Physical Therapy Korea
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• v.15 no.1
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• pp.61-68
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• 2008

The aim of the study was to evaluate the effect of a disease-specific exercise (DSE) on temporomandibular joint (TMJ) function and neck mobility in TMJ dysfunction associated with ankylosing spondylitis (AS). Ten AS patients (seven males and three females) with TMJ dysfunction were recruited for this study. The DSE included exercises to correct head and neck posture and to improve the flexibility of the neck and TMJs. The patients attended treatment three times a week for 4 weeks, averaging 1 hour each session. Assessments were performed pretreatment, posttreatment, and 6 weeks after the completion of treatment. General physical status was assessed by four clinical measures (tragus-to-wall distance, modified Schober test, lumbar side flexion, and intermalleolar distance), the Bath ankylosing spondylitis function index (BASFI), and the Bath ankylosing spondylitis disease activity index. The main outcome measures included TMJ function (craniomandibular index (CMI)), and neck mobility (flexion, extension, rotation, and lateral rotation). None of the measures of general physical status, with the exception of BASFI, were significant1y different between the pretreatment, posttreatment, and 6-week follow-up (p>.05). However, CMI and all neck movements, except for extension, significant1y improved after the treatment (p<.05). These improvements were maintained during the follow-up period. The DSE used in the present study seems to be a clinical1y useful method for managing patients with symptoms from the stomatognathic system in AS. Further studies with more subjects and longer treatment times, including the follow-up period, will be conducted to validate these findings.

• Journal of Technologic Dentistry
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• v.30 no.1
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• pp.83-96
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• 2008

This study aims to analyze the major factors in their working conditions affecting the enlargement of leisure activities of dental technicians. We also present a need for dental technicians to assign more time many different kinds of leisure activities for their quality life. To this end, we examined the status and the characteristics of dental technicians' leisure activities among the randomly selected subjects who are working in the area of Seoul, Gyonggido, and Gangwon-do through the analysis of the 311 sheets of self-administered questionnaires. The conclusions from this analysis are as follows; 1. On weekdays, non participants in leisure activities were found to be 64.0%, and in the case of weekends, the participants were reached to 70.7%. Those who enjoy any leisure activities in either of weekdays and weekends were 34.1%, 27.3% of the dental technicians did not have any leisure activities. Therefore, statistical significance was shown in the participations of leisure activities between weekdays and weekends. 2. Of the types of leisure activities in both weekdays and weekends, sports activities were ranked at the top 33.4%, 29.6% respectively, which is followed by going to the cinema/theatre/exhibitions, etc 21.9%, 26.0%, games/entertainment 14.5%, 14.8%, hobbies/cultural activities 14.1%, 12.5%, sightseeing/picnic 6.4%, 7.4%. 3. Of the differences in the characteristics of leisure activities, the types of leisure activities between weekdays and weekends showed difference in gender, company and information regarding leisure activities in age, company and the place of leisure activities, and leisure information in the marital status, career and monthly income in company, company and leisure information in the job position, which is statistically significant (p<.001). However, no statistical significance was found among the other general items of the characteristics of leisure activities. Considering only works on weekdays policy is currently permeating into almost every business sector, dental business owners or managers are advised to consider more effective time management or human resources management, such as keeping reasonable manufacturing time through cooperations with the dentists, regularity of working hours, incentive system, introduction of credible over time payment. Which will provide their staff with more times and opportunities to enjoy their leisure activities. Additionally, the concrete and feasible ways of motivating and activating the leisure activities of dental technicians are in need of further researches and studies.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.2
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• pp.302-322
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• 1998

This study was accompolished to analyze and compare the number and area of the occlusal contact points in healthy volunteers and athletes with normal occlusion. For this study, 15 athletes(13 amles and 2 females with average age 20) and 21 healthy volunteers(14 mles and 7 females with average age 20.09) were selected. The visual display acquired by scanning of occlusal record in maximal intercuspation was converted into 16 gray value image. Then, using computer program(J & Lee Occlusal Analyser), the pixel which was in definite range of the gray value was recognized, and the numbers of recognized pixel were calculated to area. The results were as follows ; 1. The average numbers of total occlusal contact feints were 31.05 in control group, and 34.67 in athlete group. The average area of total occlusal contacts was $100.25mm^2$ in control group, and $127.78mm^2$ in athlete group. 2. In control group, the average numbers of occlusal contact points were revealed in order as follows ; the first molar(8.48), the second molar(8.24), the second premolar(4.71), the lateral incisor(2.90), the first premor(2.43), the central incisor(2.19), and the canine(2.1). The least average in canine(2.1) was similar to the average(2.19) in central incisor and (2.09) in lateral incisor. In athlete group, the average numbers of occlusal contact points were revealed in order as follows ; the first molar(8.97), the second molar(8.47), the second premolar(5.60), the canine(3.80), the lateral incisor(3.33), the first premolar(2.67), and the central incisor(1.93). 3. In control group, the average areas of occlusal contact surface were revealed in order as follows ; the first molar($39.47mm^3$), the second molar($37.54mm^3$), the second premolar($9.54mm^3$) the first premolar($6.18mm^3$), canine($3.49mm^3$), the central incisor($2.76mm^3$), and the lateral incisor($1.28mm^3$). In athlete group, the average areas of occlusal contact surface were revealed in order as follows ; the first molar($44.11mm^3$), the second molar($40.69mm^3$), the second premolar($16.50mm^3$), the first premolar($9.39mm^3$), the canine($5.08mm^3$), the lateral incisor($3.7mm^3$), and the central incisor($2.25mm^3$). 4. With aging in both control and athlete group, there was a decreasing tendancy in average number of occlusal contact point, and was an increasing tendancy in average area of occlusal contact surface. In comparison at each age, both the numbers and area of occlusal contact were greater in athlete group than in control group. It was not significant in the numbers of occlusal contact points beween athlete and control group(p>0.1), but significant in the area of occlusal contact surface(p<0.03). 5. In comparision as to the kind of sports(Gymnastics : 2, Rugby : 3, Soccor : 5, Ice hocky : 5), the numbers of occlusal contact points were the most in ice hocky, and the area of occlusal contact surface was the greatest in gymnastics. With increasing a career in athlete group, there was a decreasing tendancy in average numbers of occlusal contact points and was an increasing tendancy in average area of occlusal contact surface. 6. By T-scan analyzing, the contact numbers on the anterior teeth were greater in control group than in athlete group, and on the posterior teeth were greater in athlete group than in control group. And the results acquired by T-scan were lesser than that caquired by the silicone bite records. It was not significant in the posterior teeth, but significant in the anterior teeth. In T-scan records, the numbers of occlusal contact points on second molar were the greatest, but in the silicone records, the numbers on first molar were the greatest.