• 치위생과학회지
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• 제23권4호
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• pp.378-388
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• 2023

Background: With increasing interest in health in old age, aspects of oral aging are being considered. The Korean Academy of Geriatric Dentistry recently proposed the diagnostic criteria for oral frailty in older adults in Korea. This study aimed to conduct a cross-sectional survey of factors related to oral frailty among community-dwelling older adults and identify differences in oral frailty status according to age and sex. Methods: Among 217 older adults aged ≥60 years who visited a senior center in Wonju, 206 completed all tests for oral frailty. Among them, data from those with a Korean Version of the Modified Barthel Index score ≥90 were used in the final analysis. After evaluating oral frailty diagnostic factors such as chewing ability, occlusal force, tongue pressure, oral dryness, oral cleanliness, and swallowing function, oral hypofunction was determined according to the oral frailty diagnostic criteria. Subsequently, the evaluation results were compared based on sex and age. Results: Significant differences in chewing ability, maximum occlusal pressure, and maximum tongue pressure were observed between sexes. However, these differences did not affect oral frailty diagnosis. All diagnostic factors of oral frailty, except for the risk of oral dryness and swallowing dysfunction, showed significant differences with age. However, no significant difference was observed in the prevalence of oral frailty. Additionally, this study found no relationship between sex and oral frailty factors using the oral frailty diagnostic criteria. However, it also found that age plays a significant role as an oral frailty diagnostic indicator, in addition to oral dryness and swallowing function. Conclusion: Sex and age did not affect oral frailty diagnosis. However, patients' chewing ability, occlusal force, and tongue pressure were affected by sex and age. Therefore, sex and age should be considered when diagnosing and intervening in oral frailty in the future.

• 대한치과의사협회지
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• 제22권5호통권180호
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• pp.439-446
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• 1984

The purpose of this study was observe the effects of excessive occlusal force on gingival fibroblasts and collagen fibers of dog. The experiment was performed in 5 dogs. 1 dog was used as control and 4 dogs as experimental group. In experimental group, high Sun Platinum casting metal crowns with 2.0mm thick were placed artificially onto the upper right third premolars to create the traumatic occlusion. After 3, 7, 15, 30 experimental days, the specimens were examined under electron microscope. The following results were observed: 1. In 3, 7, 15 day groups, swelling of the mitochondria in the fibroblast was observed. 2. In 7, 14, day groups, dilation of the endoplasmicreticulum in the fibroblast was observed. 3. There were no remarkable changes in the nucleus of the fibroblasts and collagen fibers. 4. In 30 day group, the changes of the mitochondria and the ER in the fibroblast were recovered to have the similar appearance with that of the control group.

• The Journal of Advanced Prosthodontics
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• 제13권4호
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• pp.216-225
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• 2021

PURPOSE. The aim of this study is to evaluate the effects of canine guidance occlusion and group function occlusion on the degree of stress to the bone, implants, abutments, and crowns using finite element analysis (FEA). MATERIALS AND METHODS. This study included the implant-prosthesis system of a three-unit bridge made of monolithic zirconia and hybrid abutments. Three-dimensional (3D) models of a bone-level implant system and a titanium base abutment were created using the original implant components. Two titanium implants, measuring 4 × 11 mm each, were selected. The loads were applied in two oblique directions of 15° and 30° under two occlusal movement conditions. In the canine guidance condition, loads (100 N) were applied to the canine crown only. In the group function condition, loads were applied to all three teeth. In this loading, a force of 100 N was applied to the canine, and 200-N forces were applied to each premolar. The stress distribution among all the components of the implant-bridge system was assessed using ANSYS SpaceClaim 2020 R2 software and finite element analysis. RESULTS. Maximum stress was found in the group function occlusion. The maximum stress increased with an increase in the angle of occlusal force. CONCLUSION. The canine guidance occlusion with monolithic zirconia crown materials is promising for implant-supported prostheses in the canine and premolar areas.

• The Journal of Advanced Prosthodontics
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• 제5권2호
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• pp.187-197
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• 2013

PURPOSE. The purpose of this study was to evaluate various core designs on stress distribution within zirconia crowns. MATERIALS AND METHODS. Three-dimensional finite element models, representing mandibular molars, comprising a prepared tooth, cement layer, zirconia core, and veneer porcelain were designed by computer software. The shoulder (1 mm in width) variations in core were incremental increases of 1 mm, 2 mm and 3 mm in proximal and lingual height, and buccal height respectively. To simulate masticatory force, loads of 280 N were applied from three directions (vertical, at a $45^{\circ}$ angle, and horizontal). To simulate maximum bite force, a load of 700 N was applied vertically to the crowns. Maximum principal stress (MPS) was determined for each model, loading condition, and position. RESULTS. In the maximum bite force simulation test, the MPSs on all crowns observed around the shoulder region and loading points. The compressive stresses were located in the shoulder region of the veneer-zirconia interface and at the occlusal region. In the test simulating masticatory force, the MPS was concentrated around the loading points, and the compressive stresses were located at the 3 mm height lingual shoulder region, when the load was applied horizontally. MPS increased in the shoulder region as the shoulder height increased. CONCLUSION. This study suggested that reinforced shoulder play an essential role in the success of the zirconia restoration, and veneer fracture due to occlusal loading can be prevented by proper core design, such as shoulder.

• 대한치과보철학회지
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• 제31권1호
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• pp.151-162
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• 1993

The author installed $3.75mm\times10mm$ $Br{\aa}nrmark$ osseointegrated implants and $3.5mm\times8mm$ I.T.I. hollow screw implants(Benefit) as a free standing abutment to replace lower left and right molars of 44-year-old female patient. Form the foregoing procedure, the author obtained the following results. 1. Free-standing $Br{\aa}nrmark$ and I.T.I. Hollow screw implants(Benefit) could be used to replace molars effectively without reduction of adjacent natural teeth, 2. Rotation of occlusal gold screw of $Br{\aa}nrmark$ implants was observed under occlusal force. 3. Adjustment of height of I.T.I. abutments was necessary in the mandibular second molar because of the limited occlusal clearance. 4. Form the oral examination, patient comments, panoramic and periapical radiographs, there were no pain, gingival imflammation and mobility, but slight reduction of alveolar bone level was shown around both implant systems. 5. Patient comments were comfortable on both systems. but the patient complained about economic problem of $Br{\aa}nrmark$ system and long treatment treatment time of both systems.

• 대한치과보철학회지
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• 제13권1호
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• pp.23-26
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• 1975

The purpose of this study was to measure the retentive force of various kinds of dental cement. Cross-cutting the half of the occlusal surface, pinholes were prepared on the dentin with No. 557 carbide bur. No. 557 steel burs were cemented in the pinholes and retentive force was measured by removing the burs with Instron testing machine. The Instron testing machine was operated at a rate of 0.2 cm per minute. The following results were obtained : 1. The retentive force of zinc phosphate cement(A), reinforced zinc oxide and eugenol cement and polycarboxylate cement were similar to each other, but that of zinc phosphate cement (A) was the highest of all. 2. The retentive force of zinc phosphate cement (B) was the lowest of all.

• 구강회복응용과학지
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• 제36권3호
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• pp.176-182
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• 2020

목적: 수복물에 교합력을 가할때 식립된 임플란트의 개수, 배열 및 위치에 따른 임플란트, 보철물 및 지지 골에 발생하는 응력의 차이를 분석하고자 한다. 연구 재료 및 방법: 하악에 임플란트가 식립되어 고정성 보철물을 지지하는 4 종류의 3D 유한요소 모형을 제작하였다. 모델 M1은 2개의 임플란트 가운데에 가공치를 배열하였고, 모델 M2는 2개의 임플란트 외측에 캔티레버 가공치를 배열하였다. 모델 M3과 M4는 3개의 임플란트를 각각 일렬로 배열되거나, 엇갈리게 배열하였다. 총 120 N 크기의 수직력과 45도 측방력을 가하였고, 유한요소 응력 분석을 시행하였다 결과: 측방력 하중에 의해 발생한 최대 응력은 수직력 하중에 의한 것 보다 임플란트 부위에서 3.4 - 5.1배 더 컸고, 지지골 내에서는 3.5 - 8.3배 더 컸다. 모델 M2 의 고정성 보철물의 캔티레버 연결부에서 가장 큰 응력이 집중되었다. 임플란트 개수가 3개인 모델들이 2개인 경우보다 더 낮은 응력이 발생하였으나 M3과 M4에서 일렬 배열과 엇갈린 배열간의 응력 발생 차이는 작았다. 결론: 임플란트 배열의 엇갈림 정도는 응력 크기에 별 차이를 발생하지 않았으나, 캔티래버의 존재나 임플란트의 개수의 차이는 큰 영향을 주었다.

• 국제물리치료학회지
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• 제12권2호
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• pp.2365-2369
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• 2021

Background: Patients with dysphagia after stroke are treated with neuromuscular electrical stimulation (NMES), but its effect on masseter muscle thickness and bite force in the oral phase is not well known. Objectives: To investigated the effect of NMES on masseter muscle thickness and occlusal force in patients with dysphagia after stroke. Design: Two group, pre-post design. Methods: In this study, 25 patients with dysphagia after stroke were recruited and allocated to either the experimental or the control groups. Patients in the experimental group were treated with NMES to the masseter muscle at the motor level for 30 minutes and were additionally treated with traditional swallowing rehabilitation for 30 minutes. In contrast, patients in the control group were only treated with traditional swallowing rehabilitation for 30 minutes. Masseter muscle thickness was measured using ultrasonography before and after intervention, and bite force was measured using an bite force meter. Results: The experimental group showed significant improvement in masseter muscle thickness and bite force compared to the control group. Conclusion: NMES combined with traditional dysphagia rehabilitation is effective in improving masseter muscle thickness and bite force in patients with dysphagia after stroke.

• 대한치과의사협회지
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• 제19권3호통권142호
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• pp.275-278
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• 1981

Traumatic occlusion is a morbid condition that is caused by repeated occlusal stresses exerted on the periodontium that exceed the physiologic limits of tissue tolerance and contribute to the breakdown of the supporting tissue of the teeth. In reviewing these cases, the authors obtained the following results. 1. Roentgenographic examination revealed the typical signs of traumatic occlusion: severe resorption of roots, destruction of alveolar bone. 2. The major factor of traumatic occlusion is abnormal occlusal force. 3. The rsorptions of roots and periodontal changes which are caused by traumatic occlusion depend on the individual variation of the physical potential. 4. The pathologic features of traumatism are basically different from those of inflammation.

• 대한치과교정학회지
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• 제44권3호
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• pp.143-153
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• 2014

An 8-years old boy with facial asymmetry and unilateral posterior crossbite on the left side received orthopedic and orthodontic treatment. During the first phase of treatment, the narrow maxillary arch was expanded using an acrylic plate. Then, the acrylic plate was used as a bite block with occlusal indentations from the construction bite that was obtained with the incisors in a coincident dental midline. After the position of the mandible was stabilized, the second phase of orthodontic treatment was initiated using fixed appliances for detailing of the occlusion. Skeletal symmetry, ideal occlusion, and coincident dental midlines were thus achieved. Functionally, occlusal force balance and masticatory muscle activity were improved, and the chewing patterns were normalized.