• 대한치주과학회:학술대회논문집
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• 1994.12a
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• pp.44-44
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• 1994

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.259-267
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• 2014

Fatigue tests were performed in various simulated body environments reflecting various factors (such as body fluids, artificial saliva) relevant within a living body. First, the fatigue limit under a simulated body environment (artificial saliva) was evaluated and the governing factors of implant fatigue strength were looked into by observing the fracture mode. The fatigue life of an implant decreased in the artificial saliva environment compared with that in the ringer environment. Furthermore, in the artificial saliva environment, the implant fracture mode was fatigue failure of fixture as opposed to the abutment screw mode in the ringer environment. In the fatigue test, corrosion products were observed on the implant in the simulated body environment. A larger amount of corrosion products were generated on the artificial saliva specimen than on the ringer specimen. It is thought that the stronger corrosion activity on the artificial saliva specimen as compared with that on the ringer specimen led to an overall decrease of fatigue life of the former specimen. In the case of the implant with a nitrided abutment screw eliminated hardened layer (TixN), a several times increase in fatigue life is achieved in comparison with tungsten carbide-coated implants.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.24-24
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• 2015

최근 생체재료의 개발이 눈부시게 발전되고 생체적합성이 우수한 표면을 요구함에 따라 생체재료의 표면처리에 대한 연구가 활발히 진행되고 있다. Laser Deposition법은 항공기 부품제조 분야에 주로 사용되고 있으며 최근에 오하이오 주립대 타이타늄합금연구센터를 중심으로 표면처리에 관한 연구가 주로 이루어졌다. 특히 이를 이용하여 치과재료의 표면처리에 응용을 시도하였다. 치과에서 응용될 수 있는 경우는 주로 임플란트는 부분 또는 완전 무치악 환자의 보철수복에 사용되는 보철물의 제작등에 사용될 수 있으며 이중에서도 특히 생체용 임플란트의 표면처리응용으로 임플란트와 조직간의 접합성을 개선하는 표면처리법으로 연구되었다. 임플란트의 성공과 실패는 물성적인 측면에서 임플란트의 형태, 표면거칠기 및 표면처리방법, 초기하중 등에 의하여 좌우되며 임플란트 재료에 작용하는 응력차폐는 생체적합성을 좌우하는 큰 요인이 되고 있다. 이를 위하여 저 탄성계수합금을 설계하지만 하중을 버티는 강도가 낮아지는 단점이 있어 레이저증착법을 이용하여 임플란트재료인 Ti6Al4V합금에 탄성계수가 낮은 Ta, Nb등을 코팅하는 방법을 통하여 이를 해결하고자하는 시도가 이루어지고 있다. 이 방법은 최근의 3D 프린팅의 원리가 되고 있다. 따라서 발표에서는 Laser Deposition방법을 이용하여 치의학분야에서 응용되고 있는 예를 강연하고 응용 가능 분야에 대하여 토론 하고자한다. 또한 펨토레이저를 이용하여 생체합금의 표면처리는 생체활성화를 더욱 증진시키며 이를 위하여 많은 연구 수행되고 있다. 본 발표에서는 매식용 합금 표면에 펨토레이저를 이용하여 텍스춰링하여 세포가 잘 성장 할 수 있는 크기의 조절함으로써 기존의 표면처리와는 다른 효과를 얻을 수 있는 장점을 알아본다. 펨토레이저를 이용하면 여러 가지 형태의 텍스춰링이 가능하며 원형, 사각형등등 자유자제로 형태의 묘사가 가능하고 깊이 또한 쉽게 조절할 수 있는 장점이 있다. 지금까지는 표면 개질에 사용되는 레이저는 주로 Nd:YAG 레이저의 파장을 반으로 줄인 녹색레이저 (${\lambda}=532nm$)를 사용하거나, 자외선파장영역의 레이저를 사용하는 경우가 일반적으로 가장 보편화되었다. 이를 이용하여 제조된 Ti합금에 펨토 초(10-15 second) 펄스폭 대역을 갖는 레이저를 이용하여 나노크기의 미세 요철을 표면에 형성한 후, 나노튜브를 형성하여 그 표면특성의 변화를 알아보고 펨토레이저가 의료분야에 적용되고 있는 예를 살펴보고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.514-516
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• 2001

본 논문은 시차를 두고 촬영된 두 장의 치과용 디지털 X-Ray 영상으로부터 임플란트 시술환자에서 자주 발생하는 임플란트 주위염을 검출하는 자동화된 시계열 분석 방안을 제안한다. 분석자에 따라서 결과의 차이를 보이는 수동적인 시계열분석방법의 문제점을 극복하고 보다 객관적이고 정략적인 결과를 얻는 방안을 제시한다. 보다 신속하고 정확한 검출을 위해서 본 연구에서는 치아의 구조 분석을 통해서 환부 탐색 영역을 줄이고 작은 변화도 민감하게 검출할 수 있는 환부영역을 분리할 수 있는 방안을 제안한다. 또한 분리된 환부의 특성을 수치적으로 표현할 수 있는 방안도 함께 제시된다.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.1
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• pp.1-8
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• 2017

Purpose: The purpose of this study is to compare the accuracy of the CT guided implant template that was produced by using an intraoral scanner according to the edentulous distance. Materials and methods: Five maxillary casts were fabricated using radiopaque acrylic resin with the second premolars, first molars, and second molars missing. Then a virtual cast was acquired by scanning each resin cast. Implant treatment was planned on the missing sites by superimposing the presurgical CT DICOM file and the virtual cast. Then the implants were placed using a surgical template followed by postsurgical CT scan. The distance and angle of the platform and apex between the presurgical implant and postsurgical implant were measured using the X, Y, and Z axis of the superimposed presurgical CT and postsurgical CT via software followed by statistical analysis using Kruskall-Wallis test and Mann-Whitney test. Results: The implant placement angle error increased towards the second molars but there was no statistically significant difference. The implant placement distance error at the platform and apex also increased towards the second molars and there was a statistically significant error at the second molars. Conclusion: Although the placement angle had no statistically significant difference between the presurgical implant and postsurgical implant, the placement distance at the platform and apex showed a larger error and a statistically significant difference at the second molar implant.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.3
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• pp.245-256
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• 2023

When restoring with a dental digital system for implant-supported prosthesis, a double digital scanning technique is required: an intraoral scan of the three-dimensional implant location and intraoral scan after placement of temporary denture or provisional prosthesis. During the intraoral scan, the use of scan body as a stable landmark can improve the accuracy of digital impression and simplify laboratory process. In this case, a full-digital system was used to plan and fabricate a custom abutment, provisional prosthesis, and definitive prosthesis. After implant placement, the scan area of the intraoral scan body connected with implant and the intraoral scan body marked on the inside of temporary denture were superimposed. Out of the superimposed files, a custom abutment and provisional prosthesis were fabricated which match the vertical dimension of temporary denture, and definitive prosthesis was fabricated based on provisional prosthesis. We report this case because result has been functionally and esthetically satisfactory by using vertical dimension and central relation set during the fabrication of temporary denture to the definitive prosthesis.

• The korean journal of orthodontics
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• v.38 no.4
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• pp.228-239
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• 2008

Objective: The aim of this study was to evaluate the strain induced in the cortical bone surrounding an orthodontic microimplant during insertion. Methods: A 3D finite element method was used to model the insertion of a microimplant (AbsoAnchor SH1312-7, Dentos Co., Daegu, Korea) Into 1 mm thick cortical bone with a pre-drilled hole of 0.9 mm in diameter. A total of 1,800 analysis steps was used to simulate the 10 turns and 5 mm advancement of the microimplant. A series of remesh in the cortical bone was allowed to accommodate the change in the geometry accompanied by the implant insertion. Results: Bone strains of well higher than 4,000 microstrain, the reported upper limit for normal bone remodeling, was observed in the bone along the whole length of the microimplant. At the bone in the vicinity of the screw tip, strains of higher than 100% was recorded. The insertion torque was calculated at approximately 1.2 Ncm which was slightly lower than those measured from the animal experiment using rabbit tibias. Conclusions: The insertion process of a microimplant was successfully simulated using the 3D finite element method which showed that bone strains from a microimplant insertion might have a negative impact on physiological remodeling of bone.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.36-42
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• 2021

Even though implant overdentures are preferentially recommended to mandibular edentulous patients, many patients may select conventional complete dentures due to cost and general condition. Proper retention and stability of conventional complete dentures in patients with severe alveolar bone resorption is difficult to achieve. To overcome the limitations, mandibular suction dentures with the closed mouth impression technique have been used. However, the previous technique requires the Frame cut back tray, the Centric tray, and the Gnathometer M. This article introduces a technique for fabricating a mandibular suction denture with common dental materials.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.67-71
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• 2023

Recently, the method of making a dental prothesis is changed in the ICT based digital way. In particular, with the emergence of the CAD/CAM or 3D printing for dental purpose, a computer based digital type is selected gradually more than an analog type. To make an implant abutment, it is possible to apply the conventional technique of making round bars, or the technique using a CNC milling machine. This study tested these two types of the techniques to find which one had more precision and a smaller error when the margin and occlusal surface was made. According to the test, the technique using a CNC milling machine to make an implant abutment had a small error and supported precise processing in terms of the margin fit and the occlusal surface. Therefore, it was found to be useful in making a custom-made prothesis.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.4
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• pp.196-203
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• 2022

Purpose: This study aimed to evaluate the accuracy and clinical usability of an identification model using deep learning for 79 dental implant types. Materials and Methods: A total of 45396 implant fixture images were collected through panoramic radiographs of patients who received implant treatment from 2001 to 2020 at 30 dental clinics. The collected implant images were 79 types from 18 manufacturers. EfficientNet and Meta Pseudo Labels algorithms were used. For EfficientNet, EfficientNet-B0 and EfficientNet-B4 were used as submodels. For Meta Pseudo Labels, two models were applied according to the widen factor. Top 1 accuracy was measured for EfficientNet and top 1 and top 5 accuracy for Meta Pseudo Labels were measured. Results: EfficientNet-B0 and EfficientNet-B4 showed top 1 accuracy of 89.4. Meta Pseudo Labels 1 showed top 1 accuracy of 87.96, and Meta pseudo labels 2 with increased widen factor showed 88.35. In Top5 Accuracy, the score of Meta Pseudo Labels 1 was 97.90, which was 0.11% higher than 97.79 of Meta Pseudo Labels 2. Conclusion: All four deep learning algorithms used for implant identification in this study showed close to 90% accuracy. In order to increase the clinical applicability of deep learning for implant identification, it will be necessary to collect a wider amount of data and develop a fine-tuned algorithm for implant identification.