• 치위협보
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• s.77
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• pp.1-12
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• 2003

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.381-395
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• 2008

Purpoose: For decades dental implants have been used widely in the field of prosthetic dentistry. However there is confusion when establishing treatment plans in cases where some teeth are remained but an insufficient number of implants can be used due to limited anatomical status and ecomomical problems. Many clinicians have tried to connect natural teeth and implants, and it still has controversy. But, there have been few studies on mechanical analysis of connecting natural teeth and implants with konus telescopic removable partial dentures. The purpose of this study was to analyze the stress distribution of prosthesis, abutment and alveolar bone when teeth and implants were connected with the konus telescopic denture, by means of 3-dimensional finite element analysis. Material and methods: The assumption of this study was that there were 2 mandibular canine (11 mm in length, 4 mm in diameter) and 2 implants(10 mm in length, 4 mm in diameter) which are located in the second premolar region. The mandible, teeth, implants, abutments, and connectors are modeled, and analyzed with the commercial software, ANSYS Version 8.1(Swanson, Inc., USA). The control group used implants instead of natural teeth. 21038 elements, 23544 nodes were used in experimental group and 107595 elements, 21963 nodes were used in control group, Stress distribution was evaluated under 150 N vertical load on 3 experimental conditions - between teeth and implants (Load case 1), posterior to implants (Load case 2), between natural teeth (Load case 3). Results: 1. In all load cases, higher von mises stress value was observed in the experimental group. 2. Maximum von miss stress observed in all load cases and all locations were as follows ; a. 929.44 Mpa in the experimental group, 640.044 Mpa in the control group in outer crown and connector - The experimental group showed 1.45 times high value compared with the control group. b. 145,051 Mpa in the experimental group, 142.338 Mpa in the control group in abutment - The experimental group showed 1.02times high value compared with the control group. c. 32.489 Mpa in the experimental group, 25.765 Mpa in the control group in alveolar bone - The experimental group showed 1.26times higher value compared with the control group. 3. All maximum von mises stress was observed in load case 2, and maxim von mises stress in alveolar bone was 32.489 Mpa at which implant failure cannot occur. 4. If maximum von mises stress is compared between two groups, the value of the experimental group is 1.02 times higher than the control group in abutment, 1.26 times higher than the control group in alveolar bone. Conclusion: If natural teeth and implants are connected with the konus telescopic denture, maximum stress will be similar in abutment, 1.26 times higher in alveolar bone than the control group. With this result, there may be possible to make to avoid konus telescopic dentures where natural teeth and implants exist together.

• 대한치과보철학회:학술대회논문집
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• 1998.11a
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• pp.44-44
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• 1998

• 대한치과보철학회:학술대회논문집
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• 2000.04a
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• pp.33-33
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• 2000

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.3
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• pp.212-217
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• 2018

Purpose: This study was to assess clinically the incidence of abutment screw loosening of posterior implant-supported fixed prosthesis and its affecting factors. Materials and methods: 391 implant-supported crowns restored from January 2013 to January 2016 were included in this study. All restorations were fabricated with either a single crowns or a splinted crown, and cemented with temporary cement. The incidence of abutment screw loosening is investigated and gender, restoration position, opposing teeth, restoration type, abutment connection type were assessed as possible factors affecting abutment screw loosening. Results: During the observation period (2 - 5 years), abutment screw loosening was found in 29 restorations (7.4%). It took 3 to 48 months (means 19.5 months) to loose the screw, and three of these implants were fractured. Among the factors considered, there were statistically significant differences at abutment screw loosening rate between molar group (9.4%) and premolar group (2.6%) (P<.019). According to the type of opposing teeth, there were statistically significant differences between nature teeth (74.7%) and implant (25.0%), removable denture (3%) (P<.019). The other possible factors did not have a significant effect on loosening of the abutment. Conclusion: The incidence of abutment screw loosening in posterior restoration was 7.4%. Abutment screw loosening were more likely to occur in molars group than premolar group, and according to the opposing teeth, there were the greatest frequency in nature teeth than implant and removal denture. There was a statistically significant difference.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.479-489
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• 2008

Statement of the problem: Under anatomical limitations on maxillary posterior region, a poor crown-to root ratio acting on dental implants can result in undesirable stress in surrounding bone, which in turn can cause bone defects and eventual failure of implants. Purpose: The purpose is to compare stress distribution due to different crown-root ratio and effect of splinting between natural teeth and implants in maxillary molar area under different loads. Material and methods: Analysis of stress arising supporting bone of the natural teeth and the implant was made with 3-dimensional finite element method. The model simulated naturel teeth was made with 2nd premolar and 1st molar in the maxillary molar region (Model T). The model simulated implants placed on same positions with two parallel implants of Straumann Dental Implant cemented abutment (Model I). Each model was designed in different crown-root ratio (0.7:1, 1:1, 1.25:1) and set cement type gold crown to make it non-splinted or splinted. After that, 300 N force was loaded to each model in five ways (Load 1: middle of occlusal table, Load 2: middle of buccal cusp, Load 3: middle of lingual cusp, Load 4: horizontal load to buccal cusp of anterior abutment only, Load 5: horizontal load to middle of buccal cusp of each abutment), and stress distribution was analyzed. Results and conclusion: On all occasions, stress was concentrated at the cervical region of the implant. Under load 1, 2 and 3, stress was not increased even when crown-root ratio increases, but under load 4 and 5, when crown-root ratio increases, stress also increased. There was difference in stress values between natural teeth and implants when crown-root ratio gradually increases; In case of natural teeth, splinting decreased stress under vertical and horizontal loads. In case of implants, splinting decreased stress under vertical loads 1,2 and 3, but increased maximal stress under loads 2 and 3. Under horizontal loads, splinting decreased stress, however the effect of splinting decreased under load 5 than load 4. Furthermore, the stress was increased, when crown-root ratio is 1.25:1. Clinical implications: This limited finite element study suggests that the stress on supporting bone may be increased under non-axial loads and poor crown-root ratio. Under poor crown-root ratio, excessive stress was generated at the cervical region of the implant, and decreased splinting effect for stress distribution, which can be related to clinical failure.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.1
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• pp.9-17
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• 2022

Purpose: The purpose of this study is to investigate how open contacts impact the natural teeth and dental implant prostheses. Materials and Methods: Following criteria were used to select 20 implant crowns with open proximal contacts as the experimental group (Group A): the restorations were delivered in Chosun University Dental Hospital between 2008 and 2018, the restorations are in the posterior region, opposing teeth are fixed dental prostheses, neighboring teeth are sound natural teeth, the patient had been on the maintenance program for at least 3 years. Another 20 implant crowns with closed proximal contacts were selected as the control group (Group B) using the same criteria. Between the two groups, dental caries and food impaction of the neighboring natural teeth and marginal bone-loss of the implants were compared and evaluated. Results: There was no statistically significant difference between Group A and Group B in the occurrence rates of dental caries, food impaction, and marginal bone-loss. The amount of marginal bone-loss, however, revealed statistically significant differences between the two groups, with Group A showing 0.80 ± 0.39 mm loss and Group B showing 1.1 ± 0.43 mm loss. Conclusion: Implant prostheses with open contacts could be clinically considered in select cases as such restorations revealed no harmful effects on neighboring teeth and implant restorations within the perimeters of this study.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.4
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• pp.378-386
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• 2015

Overdenture has the advantage of improving the stability and retention of the denture but the abutment may be easily affected by caries or periodontal disease and the thin denture can be easily broken. The magnetic attachment overdenture has a high vertical retention but a low horizontal retention, thus, exerting a less disruptive force to the abutment or implant and shows less abrasion or damage compared to other mechanical retainers. Denture fractures in overdenture is caused by the thin denture base as the attachment is inserted, but it may also be caused by the difference in detrusion between soft tissue and hard tissue, and between an implant and a natural tooth. To compensate this shortcoming, a magnetic attachment with a silicone ball inserted in the magnet was developed as we report a successful case using this specific type of magnetic attachment overdenture.

• Journal of the KSME
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• v.26 no.5
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• pp.389-393
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• 1986

고유치는 여러 공학문제에서 중요하다. 예를들어 비행기의 안전성은 어떤 행렬(matrix)의 고유 치에 의해서 결정된다. 보의 고유진동수는 실제로 행렬의 고유치이다. 좌굴(buckling) 해석도 행렬의 고유치를 구하는 문제이다. 고유치는 여러 수학적인 문제의 해석에서도 자연히 발생한다. 상수계수 일계연립상미분방정식의 해는 그 계수행렬의 고유치로 구할 수 있다. 또한 행렬의 제곱의 수렬 $A,{\;}A^{2},{\;}A^{3},{\;}{\cdots}$의 거동은 A의 고유치로서 가장 쉽게 해석할 수 있다. 이러한 수렬은 연립일차방정식(비선형)의 반복해에서 발생한다. 따라서 이 강좌에서는 행렬의 고유치를 수치적으로 구하는 문제에 대하여 고찰 하고자 한다. 실 또는 보소수 .lambda.가 행렬 B의 고유치라 함은 영이 아닌 벡터 y가 존재하여 $By={\lambda}y$ 가 성립할 때이다. 여기서 벡터 y를 고유치 ${\lambda}$에 속하는 B의 고유벡터라 한다. 윗식은 또 $(B-{\lambda}I)y=0$의 형으로도 써 줄 수 있다. 행렬의 고유치를 수치적으로 구하는 방법에는 여러 가지 방법이 있으나 그 중에서 효과있는 Danilevskii 방법을 소개 하고자 한다. 이 Danilevskii 방법에 의하여 특 성다항식(Characteristic polynomial)을 얻을 수 있고 이 다항식의 근을 얻는 방법 중에 Bairstow 방법 (또는 Hitchcock 방법)이 있는데 이에 대하여 아울러 고찰하고자 한다.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.31 no.2
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• pp.47-55
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• 2022

Food impaction due to proximal space opening after implant restoration is a very common phenomenon in patients who have implant prosthesis. This occurs because the movement mechanism between the implant and the tooth is different, and it occurs about 30-60% over time. Contributing factors include the arch (mandible), region (posterior teeth), adjacent teeth (non-vital teeth), and antagonist teeth (natural teeth or implants), etc. While this phenomenon cannot be prevented, efforts should be made to minimize it. In order to have an ideal proximal contact as much as possible, the concave shape or the prominent lower proximal shape should be modified to create a symmetrical proximal shape. with the buccal dentate in the upper third height should be adjusted. Other conditions should be modified so that the heights of the marginal ridges are similar. Since an irregular occlusal plane is a cause of poor prognosis, food impaction should be minimized by restoring the ideal occlusal plane by correcting the extruded antagonist and reduction of the disto-buccal cusp.