• 대한치과보철학회지
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• 제36권2호
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• pp.389-423
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• 1998

This investigation was designed to determine the effectiveness of the posterior occlusal schemes on masticatory activity during mastication in complete denture. Twelve edentulous subjects were selected for this study. All subjects had no past history and no functional abnormality on masticatory system and TMjoint. And, they had residual ridge of favorable morphology, firm mucosa and Class I skeletal jaw relationship, Twelve experimental denture with interchangeable occlusions(0-degree teeth, 30-degree teeth, Levin teeth and S-A teeth) were constructed for this study. The masticatory performance was analyzed by means of standard sieve(10, 16, 20, 30sieve), and the electrical activity from selected muscles(Temporalis and Masseter muscle) was recorded simultaneously with electromyography (Bio-Pak system) as the subject masticated test foods (rice, peanut and gum) with four different occlusal schemes. Mandibular movement was, also, measured with Sirognathography(Bio-Pak system). These recordings were performed in immediately, after 1 week and after 2 weeks of insertion of complete denture. The results were as fellows; 1. The average masticatory performance of 0-degree artificial teeth was higher than any other artificial teeth. 2. Masticatory performance in denture wearer was affected preferentially by food and artificial occlusal schemes. 3. During chewing, there was a statistical difference of EMG activity between masseter and temporal muscle(p<0.01). Especially, EMG activity of working masticatory muscle was highly affected by food rather than by artificial occlusal schemes. 4. In denture wearer, the velocity of opening was not affected by food, whereas, the velocity of closing was faster in soft food chewing than in hard food chewing, and the amount of vertical displacement was grater in chewing of soft and large bolus than in chewing of hard and small bolus. However, the amount of lateral displacement showed conversely(p<0.05). 5. It was considered that masticatory performance in denture wearer is not affected by the condition of residual ridge. the history of denture wear, the preference, the adaptation to artificial teeth and the total mesiodistal length of artificial posterior teeth.

• 대한치과보철학회지
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• 제34권3호
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• pp.539-573
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• 1996

This investigation was designed to determine the effectiveness of the posterior occlusal schemes on masticatory activity during mastication in complete denture. Twelve edentulous subjects were selected for this study. All subjects had no past history and no functional abnormality on masticatory system and TMjoint. And, they had residual ridge of favorable morphology, firm mucosa and Class I skeletal jaw relationship, Twelve experimental denture with interchangeable occlusions(0-degree teeth, 30-degree teeth, Levin teeth and S-A teeth) were constructed for this study. The masticatory performance was analyzed by means of standard sieve(10, 16, 20, 30sieve), and the electrical activity from selected muscles(Temporalis and Masseter muscle) was recorded simultaneously with electromyography(Bio-Pak system) as the subject masticated test foods (rice, peanut and gum) with four different occlusal schemes. Mandibular movement was, also, measured with Sirognathography(Bio-Pak system). These recordings were performed in immediately, after 1 week and after 2 weeks of insertion of complete denture. The results were as follows; 1. The average masticatory performance of 0-degree artificial teeth was higher than any other artificial teeth. 2. Masticatory performance in denture wearer was affected preferentially by food and artificial occlusal schemes. 3. During chewing, there was a statistical difference of EMG activity between masseter and temporal muscle(p<0.01). Especially, EMG activity of working masticatory muscle was highly affected by food rather than by artificial occlusal schemes. 4. In denture wearer, the velocity of opening was not affected by food, whereas, the velocity of closing was faster in soft food chewing than in hard food chewing, and the amount of vertical displacement was grater in chewing of soft and large bolus than in chewing of hard and small bolus. However, the amount of lateral displacement showed conversely (p<0.05). 5. It was considered that masticatory performance in denture wearer is not affected by the condition of residual ridge, the history of denture wear, the preference, the adaptation to artificial teeth and the total mesiodistal length of artificial posterior teeth.

• Journal of Korean Dental Science
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• 제17권1호
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• pp.14-35
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• 2024

The temporomandibular joint (TMJ) is one of the most unique joints in the human body that orchestrates complex movements across different orthogonal planes and multiple axes of rotation. Comprising the articular eminence of the temporal bone and the condylar process of the mandible, the TMJ integrates five major ligaments, retrodiscal tissues, nerves, and blood and lymph systems to facilitate its function. Cooperation between the contralateral TMJ and masticatory muscles is essential for coordinated serial dynamic functions. During mouth opening, the TMJ exhibits a hinge movement, followed by gliding. The health of the masticatory system, which is intricately linked to chewing, energy intake, and communication, has become increasingly crucial with advancing age, exerting an impact on oral and systemic health and overall quality of life. For individuals to lead a healthy and pain-free life, a comprehensive understanding of the basic anatomy and functional aspects of the TMJ and masticatory muscles is imperative. Temporomandibular disorders (TMDs) encompass a spectrum of diseases and disorders associated with changes in the structure, function, or physiology of the TMJ and masticatory system. Functional and pathological alterations in the TMJ and masticatory muscles can be visualized using various imaging modalities, such as cone-beam computed tomography, magnetic resonance imaging, and bone scans. An exploration of potential pathophysiological mechanisms related to the TMJ anatomy contributes to a comprehensive understanding of TMD and informs targeted treatment strategies. Hence, this narrative review presents insights into the fundamental functional anatomy of the TMJ and pathological changes that evolve with TMD progression.

• Journal of Oral Medicine and Pain
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• 제46권4호
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• pp.155-160
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• 2021

The masticatory muscle disorder is the most common problem that patients with temporomandibular disorder often complain. For such complaints, treatment is directed towards reducing hyperactivity of muscles or effects of the central nervous system. However, if nonspecific occlusal change or pain persists, it is necessary to consider that muscle weakness might be the cause of the persistence of temporomandibular disorder. Stabilization of occlusion and improvement of the pain symptoms were achieved in both cases through the chewing gum exercise. This exercise may enable masticatory movements done in normal function by using muscle engram and achieve reinforcement of the masticatory muscles with balanced, simultaneous contacts of the teeth. In addition, it may be a viable method for treating temporomandibular disorders that do not respond well to conventional mandibular stabilization therapies.

• 대한치과보철학회지
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• 제46권6호
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• pp.591-601
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• 2008

STATEMENT OF PROBLEM: The improvement in oral function and comfort from the dental implant appears to depend on the particular type of implant support used with the denture. The number and positioning of implants have an influence on the force transfer and subsequent stress distribution around implants. Nevertheless, a quantitative comparison has not been made between the types of implant prosthesis used with different materials compared to conventional complete denture. PURPOSE: The objective of this study is to assess the masticatory performance, bite force and impact of two different type of implant supported prostheses on oral health-related quality of life compared to conventional complete denture with GOHAI, validated oral-specific health status measures, the sieving method, and the Prescale Dental System. MATERIAL AND METHODS: From the years 1999 to 2006, a total of 30 completely edentulous patients in a single arch were selected from the Yonsei University Dental Hospital, Department of Prosthodontics and Implant Clinic in Seoul, S. Korea. Patients were divided into 3 groups of 10 each. Group HR was restored with fixed-detachable hybrid prostheses with resin teeth. Group FP had fixed dentures with porcelain teeth while Group CD had a complete denture. The masticatory performance was compared between 3 groups. RESULTS: The results showed a significant improvement in oral health-related quality of life with dental implants compared to a conventional denture in GOHAI comparison. Overall, implant prostheses showed a higher masticatory performance ($S_{50}$) and maximum bite force compared with conventional dentures (P < .05) but no differences between different implant supported prostheses (P > .05). CONCLUSION: Within the limitation of this study, the numbers of implant and material of implant prostheses does not appear to impact patient satisfaction, masticatory performance or bite force.

• 구강회복응용과학지
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• 제19권1호
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• pp.1-6
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• 2003

취약한 구강 건강은 손상된 저작의 기능을 유발할 수 있다. 음식의 선택에서 저작의 기능이 중요한 역할을 하는지는 아직 까지도 논쟁의 여지가 있을지라도, 손상된 저작의 기능은 부적절한 음식의 선택을 하게끔하며, 따라서 영양의 섭취를 변화시킨다. 만약 이러한 가설이 맞다면, 저작 기능의 결핍은 일반적 건강에 해로운 것일 것이다. 취약한 구강의 건강과 특정한 위장의 질환 사이의 관계는 비록 과학적으로 확립되지는 않았을지라도 제안되어 왔다. 공공 건강의 정책은 자연치아를 보존함으로써 적절한 영양의 섭취를 가능케 하는 것을 강조하여야 하며, 치과의사들은 의치의 사용과 관련된 영양의 위험을 의식하여야 할 것이다.

• 대한치과보철학회지
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• 제25권1호
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• pp.269-279
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• 1987

The purpose of this study was to obtain basic data needed to clinical diagnosis and treatment by investigating the occlusal wear facets and those related factors. Sixty-six subjects, ranging from 24 to 26 years of age without symptoms of stomatognatic system, were selected from dental students in Chosun University. The area of occlusal wear facets was measured and twenty subjects were selected, and divided into two groups (Group I and Group II). The Group I had small facet areas, and the Group II had large facet areas. These two groups were investigated into right and left side wear facet areas, vertical overlaps, occlusion types of working side, masticatory muscle activities, and asymmetry of right and left side masticatory muscle function. The results were as follows: 1. The average wear facet areas of all subjects was $22.84{\pm}88.95mm^2$, and Group I and Group II were $96.12{\pm}32.00mm^2$ and $372.94{\pm}65.63mm^2$ respectively. 2. The right and left wear facet areas of Group I were $46.72{\pm}14.36mm^2$ and $49.40{\pm}21.46mm^2$ respectively. The right and left wear facet areas of Group II were $175.27{\pm}45.75mm^2$ and $185.69{\pm}45.37mm^2$ repsectively. 3. The vertical overlap of Group I and Group II was $3.88{\pm}0.81mm$ and $2.88{\pm}1.14mm $ respectively. 4. Most of the Group I had Canine protection occlusion (80%), and most of the Group II had Group function occlusion (80%). 5. The masticatory muscle activities at rest position, maximum bite, habitual chewing, right and left unilateral chewing were greater in Group II than in Group I, especially in the masseter muscle of working side at right and left unilateral chewing. (P<0.01). 6. The asymmetry of right and left wear facets and masticatory muscle activities were greater in Group II than in Group I. (P<0.01).

• 대한치과보철학회지
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• 제36권4호
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• pp.533-548
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• 1998

The purpose of this study was to investigate the influence of balancing interference on the mandibular movement and masticatory muscle activity. 5 subjects(male. average age of 24.3) without dysfuction in masticatory system were selected. The balancing interference was provided by construction of cast metal crown and onlay on the upper and lower first molars. Clinical examination, changes displacement and velocity, and muscle activity were recorded and analyzed by means of BioPak system(Bioresearch Inc., Milwaukee Wisconsin. USA). The results were as follows ; 1. In clinical examination, various symptoms were reported by all subjects after application of interference. Almost symptoms were subsided after elimination of interference. 2. In the border movements in frontal plane, lateral border movement toward non-interference side was changed according to the interference after application of interference. Immediately after removal of interference, border movements' pattern was recovered as same as before experiment. 3. During gum chewing on the non-interference side, horizontal movement was decreased immediately after application of interference(p<0.05). 1 week after application of interference, horizontal movement was more decreased in 3 subjects and showed a chopping type masticatory stroke. But in 2subjects, horizontal movement was increased to avoid interference. 4. In EMG of the mandibular rest position, no significant changes were showed in the experiment period(p>0.05). 5. During gum chewing on the interference side, the activity of opposite temporal muscle was increased immediately after application of interference(p<0.05). 1 week after application of interference. The activity of ipsilateral temporal muscle and left and right masseter muscles was increased (p<0.05). 1 week after elimination of interference, increased muscle activity was recovered about the same level as before experiment. 6. During gum chewing on the non-interference side, 1 week after application of interference, the activity of ipsilateral temporal muscle was increased (p<0.05). 1 week after elimination of interference. increased muscle activity was returned about the same level as before experiment.

• Journal of Korean Academy of Oral Health
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• 제42권4호
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• pp.159-166
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• 2018

Objectives: The aim of this study was to investigate the association between masticatory ability, oral health-related quality of life, and cognitive function in an elderly population using structural equation modeling. Methods: A total of 308 subjects, aged 65 years and over, were recruited from the senior citizen center in Daegu, South Korea and provided consent for inclusion in the study. The Korean version of the Mini-Mental State Examination (K-MMSE) was used to assess the level of cognitive function. Masticatory ability was evaluated through chewing tests, patient-perceived masticatory function and, measurement of relative occlusal forces on molar teeth using the T-Scan $III^{(R)}$ system. All data were analyzed using ${\chi}^2$ tests, t-tests, and one-way ANOVA in SPSS version 23.0 for windows. Structural equation modeling was performed using SPSS AMOS version 22.0. Results: There was a significant association between cognitive function and molar teeth occlusal force. Ability of food chewing score and patient-perceived masticatory function could affect oral health-related quality of life (P>0.05). Higher occlusal forces on molar teeth, compared to anterior teeth, positively correlated with higher cognitive function. Conclusions: These results suggest that an individual's oral health condition could affect molar teeth occlusal forces and may be related to a risk of developing dementia. Therefore, there is a need for implementing nation-wide policies to improve oral health, such as masticatory function, in the elderly population.

• The Journal of Advanced Prosthodontics
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• 제12권6호
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• pp.329-337
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• 2020

PURPOSE. To verify the influence of computer-aided design/computer-aided manufacturing (CAD/CAM) implant-supported prostheses manufactured with cobalt-chromium (Co-Cr) and zirconia (Zr), and whether ceramic application, spark erosion, and simulation of masticatory cycles modify biomechanical parameters (marginal fit, screw-loosening torque, and strain) on the implant-supported system. MATERIALS AND METHODS. Ten full-arch fixed frameworks were manufactured by a CAD/CAM milling system with Co-Cr and Zr (n=5/group). The marginal fit between the abutment and frameworks was measured as stated by single-screw test. Screw-loosening torque evaluated screw stability, and strain analysis was explored on the implant-supported system. All analyses were performed at 3 distinct times: after framework manufacturing; after ceramic application in both materials' frameworks; and after the spark erosion in Co-Cr frameworks. Afterward, stability analysis was re-evaluated after 106 mechanical cycles (2 Hz/150-N) for both materials. Statistical analyses were performed by Kruskal-Wallis and Dunn tests (α=.05). RESULTS. No difference between the two materials was found for marginal fit, screwloosening torque, and strain after framework manufacturing (P>.05). Ceramic application did not affect the variables (P>.05). Spark erosion optimized marginal fit and strain medians for Co-Cr frameworks (P<.05). Screw-loosening torque was significantly reduced by masticatory simulation (P<.05) regardless of the framework materials. CONCLUSION. Co-Cr and Zr frameworks presented similar biomechanical behavior. Ceramic application had no effect on the biomechanical behavior of either material. Spark erosion was an effective technique to improve Co-Cr biomechanical behavior on the implant-supported system. Screw-loosening torque was reduced for both materials after masticatory simulation.