• Journal of Oral Medicine and Pain
• /
• 제37권2호
• /
• pp.93-105
• /
• 2012

치기공과 교육과정에서 다루어지는 보철 및 교정 치과기공물 제작 방법을 습득하기 위한 실습과목은 기능적인 영역이 강조되고 있으므로 학습자의 능력과 개인차를 충분히 고려하여 학습자의 다양한 요구에 부응할 수 있는 교수 학습모형이 필요하다. 이에 저자는 교수 1인이 다수의 학습자들을 대상으로 동시에 실습을 진행해 가는 상황에 대처할 수 있는 교수 학습법을 개발하였다. 시각적 효과에 익숙해져 있는 신세대 학생들의 특성을 고려하여 반복학습이 가능한 동영상을 활용한 온라인 실습교육과 오프라인 실습교육을 혼합한 단계적 모델링(Layers of Modeling)의 교수 학습모형을 시도하였다. 실습과정을 설명하는 동영상을 실습 일 주일 전에 e-클래스에 올려 예습하고 오도록 하고, 수업시간 교수자가 직접 실습과정을 시연하였다. 또한 전 주의 실기성적에 따라 실습실 내 학생들의 좌석배정을 하여 학업성취수준이 높은 학생과 낮은 학생을 짝지어 앉게 하여 개별실습 단계에서 동료지도법이 적용되도록 하여 학업성취수준이 낮은 학생에게 즉각적이고 개별적인 피드백이 자주 제공되도록 하였다. 수업 중에는 실습지침서에 실습결과물에 대한 자가평가를 하여 교수자의 점검을 받도록 하고 수업 후에는 동영상에서의 실습결과물과 비교, 분석하여 반성적 사고를 하도록 하였다. 그 결과 이러한 교수 학습모형은 학습자간 학업성취도의 격차를 좁히는 문제에 있어 해결의 가능성을 보여주어 학업성취도 향상에 긍정적인 영향을 주었다고 볼 수 있다.

• 대한치과기공학회지
• /
• 제41권2호
• /
• pp.63-69
• /
• 2019

Purpose: The purpose of this study is to evaluate the effect of CAD/CAM system milling tool wear on the marginal and internal fit of PMMA implant interim prosthesis three-dimensional manner. Methods: A total of 20 crowns were fabricated with CAD/CAM method. Their designs were unified to first molar of the left maxilla. The Customized abutments were prepared and scanned with on optical model scanner. Five crowns were milled by the newly replaced tool (1st milling), and 15 crowns were milled by 2nd, 3rd, 4th milling tool. The marginal and internal fit of 20 interim crowns were measured using the triple-scan protocol. Results: Statistically significant difference was found between the $1^{st}$ milling group ($51.8{\pm}14.6{\mu}m$) and the $3^{rd}$, $4^{th}$ milling group ($128.6{\pm}43.8{\mu}m$, $146.2{\pm}38.1{\mu}m$, respectively) at the distal margins. In the mesial margins, There was a statistically significant difference between the $1^{st}$ milling group ($63.6{\pm}25.9{\mu}m$) and the $3^{rd}$, $4^{th}$ milling group ($137.2{\pm}25.9{\mu}m$, $186.8{\pm}70.6{\mu}m$, respectively). In the distal line angle, significant difference was found between the $1^{st}$, $2^{nd}$, $3^{rd}$ milling groups and the $4^{th}$ milling group. In the mesial axial wall, significant difference was found between the $1^{st}$ milling group ($52.2{\pm}20.3{\mu}m$) and the $3^{rd}$, $4^{th}$ milling groups ($22.8{\pm}8.8{\mu}m$, $7.8{\pm}5.7{\mu}m$). Conclusion: As a result of the experiment, decrease of the marginal and internal fit was statistically significant as the number of machining cycles increased. In order to produce clinically excellent restorations, it is recommandable to consider the condition of the milling tool wear, when designing the restoration with CAD program.

• 한국재료학회지
• /
• 제15권10호
• /
• pp.671-677
• /
• 2005

Ti and Ti alloys are known to have excellent corrosion properties, which is an important aspect for biocompability of these implants in human body. In our study, four types of samples (Cp-Ti, Ti-6Al-4V, $0.5wt.\%$ Fe-Ti and ECAP Ti) were tested for their apatite forming ability and corrosion properties. The micropolished samples were treated with 5M NaOH solution at $60^{\circ}C$ for 24 hours. Each samples was gently washed with distilled water and heat-treated at 600"C for 1 hour. The heat-treated samples were soaked in Simulated Body Fluid (SBF) solution at $36.5^{\circ}C$ in an incubator for different period of time. The test revealed that $0.5 wt.\%$ Fe-Ti showing faster apatite growth on the surface (7th day) compared to other samples. Polarization curve test (PCT) was also carried out to determine the corrosion resistance of each samples in SBF solution. ECAP-Ti showed highest corrosion resistance compared to any other samples. $0.5wt.\%Fe-Ti$ showed higher corrosion potential and corrosion current compared to other samples.

• 대한치과보철학회지
• /
• 제40권3호
• /
• pp.275-286
• /
• 2002

Statement of problem. Surface alteration of the implant screws after function may be associated with mechanical failure. Theses metal fatigue appears to be the most common cause of structural failure. Purpose. The purpose of this study was to evaluate surface alteration of the implant screws after function through the examination of used and unused implant screws in SEM(scanning electron microscope). Materials and methods. In this study, abutment screws(Steri-oss, 3i), gold retaining screw(3i) and titanium retaining screw(3i) were retrieved from patients. New, unused abutment and retaining screws were prepared for control group. Each of the old, used screws was retrieved with a screwdriver. And retrieved implant complex of Steri-oss system was prepared for this study. Then, SEM investigation and EDS analysis of abutment and retaining screws were performed. And SEM investigation of cross-sectioned sample of retrieved implant complex was performed. Results. In the case of new, unused implant screws, as maunfactured circumferential grooves are regularly examined and screw thread are sharply remained. Before ultrasonic cleansing of old, used implant screw, a lot of accumulation and corrosion products were existed. After ultrasonic cleansing of old, used implant screws, circumferential grooves as examined before function were randomly deepened and scratches increased. Also, dull screw thread was examined. More surface alterations after function were examined in titanium screw than gold screw. And more surface alteration was examined when retrieved with driver than retrieved without driver. Conclusions. These surface alteration after function may result in the screw instability. Regularly cleansing and exchange of screws was recommended. We recommend the use of gold screw rather than titanium screw, and careful manipulation of the driver.

• 한국분말재료학회지
• /
• 제20권5호
• /
• pp.376-381
• /
• 2013

Spherical Ti-6Al-4V powders in the size range of 250 and 300 ${\mu}m$ were uniformly doped with nano-sized hydroxyapatite (HAp) powders by Spex milling process. A single pulse of 0.75-2.0 kJ/0.7 g of the Ti-6Al-4V powders doped with HAp from 300 mF capacitor was applied to produce fully porous and porous-surfaced Ti-6Al-4V implant compact by electro-discharge-sintering (EDS). The solid core was automatically formed in the center of the compact after discharge and porous layer consisted of particles connected in three dimensions by necks. The solid core increased with an increase in input energy. The compressive yield strength was in a range of 41 to 215 MPa and significantly depended on input energy. X-ray photoelectron spectroscopy and energy dispersive x-ray spectrometer were used to investigate the surface characteristics of the Ti-6Al-4V compact. Ti and O were the main constituents, with smaller amount of Ca and P. It was thus concluded that the porous-surfaced Ti-6Al-4V implant compacts doped with HAp can be efficiently produced by manipulating the milling and electro-discharge-sintering processes.

• Journal of Periodontal and Implant Science
• /
• 제46권3호
• /
• pp.152-165
• /
• 2016

Purpose: This study investigated the effects of bone density and crestal cortical bone thickness at the implant-placement site on micromotion (relative displacement between the implant and bone) and the peri-implant bone strain distribution under immediate-loading conditions. Methods: A three-dimensional finite element model of the posterior mandible with an implant was constructed. Various bone parameters were simulated, including low or high cancellous bone density, low or high crestal cortical bone density, and crestal cortical bone thicknesses ranging from 0.5 to 2.5 mm. Delayed- and immediate-loading conditions were simulated. A buccolingual oblique load of 200 N was applied to the top of the abutment. Results: The maximum extent of micromotion was approximately $100{\mu}m$ in the low-density cancellous bone models, whereas it was under $30{\mu}m$ in the high-density cancellous bone models. Crestal cortical bone thickness significantly affected the maximum micromotion in the low-density cancellous bone models. The minimum principal strain in the peri-implant cortical bone was affected by the density of the crestal cortical bone and cancellous bone to the same degree for both delayed and immediate loading. In the low-density cancellous bone models under immediate loading, the minimum principal strain in the peri-implant cortical bone decreased with an increase in crestal cortical bone thickness. Conclusions: Cancellous bone density may be a critical factor for avoiding excessive micromotion in immediately loaded implants. Crestal cortical bone thickness significantly affected the maximum extent of micromotion and peri-implant bone strain in simulations of low-density cancellous bone under immediate loading.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제27권1호
• /
• pp.85-92
• /
• 2005

Reconstruction of defect in the anterior part of the maxilla to enable implant placement or prothesis is a complicated treatment due to the anatomical position and lack of soft tissues. Two cases are presented in which autogenous iliac PMCB(particulate marrow and cancellous bone) with titanium mesh were used for premaxilla reconstruction and alveolar bone repair of the anterior maxillas prior to denture and implants fixation respectively. Cancellous bone from the anterior iliac crest was compressed and placed against a titanium mesh fixed to the bone of palate in a patient with severe defect of the anterior maxilla. There were no problem in the healing, and the anterior maxillas of two patients had increased height and width during the initial healing and remodeling. The clinical reports describe the use of titanium mesh for reconstruction of premaxilla. Autogenous bone grafts were harvested from the iliac crest and were loaded on a titanium mesh that were left in the patient's maxilla for 6 months before they were removed respectively. The radiographic analysis demonstrated that a 10mm vertical ridge augmentation had been achieved. In guided bone regeneration, the quantity of bone regenerated under the barrier has been demonstrated to be directly related to the amount of the space under the membrane. This space can diminish as a result of membrane collapse. To avoid this problem which involved the use of a titanium mesh barrier to protect the regenerating tissues and to achieve a rigid fixation of the bone segments, were used in association with autologous bone in 2 cases. The aim of this study was to evaluate the capability of a configured titanium mesh to serve as a mechanical and biologic device for restoring a vertically defected premaxilla.

• Macromolecular Research
• /
• 제17권9호
• /
• pp.703-708
• /
• 2009

Silk fibroin scaffolds were examined as a biomaterial option for tissue-engineered cartilage-like tissue. In tissue engineering for cartilage repair using a scaffold, initial chondrocyte-material interactions are important for the following cell behaviors. In this study, the surface of nanofibrous silk fibroin (NSF) meshes was modified by a microwave-induced argon plasma treatment in order to improve the cytocompatibility of the meshes used as cartilaginous grafts. In addition, the effects of a plasma treatment on the cellular behavior of chondrocytes on NSF were examined. The plasma treatment resulted in an increase in the hydrophilicity of NSF meshes suggesting that the cytocompatibility of the mesh might be improved. Furthermore, the human articular chondrocytes showed higher viability on the surface-modified NSF meshes. These results suggest that the surface modification of NSF meshes by plasma can enhance the cellular behavior of chondrocytes and may be used in tissue engineering.

• 디지털융복합연구
• /
• 제13권7호
• /
• pp.283-292
• /
• 2015

본 연구는 의료기관인증제도 도입에 따른 환자안전과 의료서비스의 질이 병원경영활동에 미치는 복합영향을 확인하고 조직문화의 매개효과를 파악하고자 하였다. 이를 위해, 2014년 6월말까지 의료기관인증을 획득한 대구 경북지역에 위치하는 300병상 미만과 300병상 이상, 6개 의료기관 종사자를 대상으로 2014년 9월 22일부터 4주간 설문조사 하였다. 해당 병원에서 1년 이상 근무한 377명을 연구대상으로 하였다. 연구결과, 300병상 미만 중소병원과 300병상 이상 병원 및 종합병원 모두, 환자안전과 의료의 질, 조직문화와 병원경영활동은 변수 간 정(+)의 상관관계가 있는 것으로 나타났다. 환자안전과 의료의 질, 병원경영활동 사이에 조직문화가 부분 매개효과가 있는 것으로 나타났으며 인과효과가 높았다. 따라서 의료기관인증제도 도입에 따른 환자안전과 의료의 질 향상 활동은 병원경영활동을 증진시키는데 효과가 있다 여겨진다.

• 대한정형도수물리치료학회지
• /
• 제17권2호
• /
• pp.11-17
• /
• 2011

Background: To evaluate the influences of Eye movement program applied to elderly people on static balance. Methods: The subjects consisted of fourteen elderly people. The subjects were divided into two group. The control group (n=7) received no exercise and/or stimulation. The Eye movement program training (E/P) group (n=7) performed balance training using word card and batom. E/P group were accomplished during 4weeks (5 day/week, 60 min/day). All tests were completed before and after experiment. The static balance ability was measured by normal standing when eye open and close on good balance system, respectively. For each case, the experimental data were obtained in 3 item; mean X speed, mean Y speed and velocity moment. Results: The result of this study were as follows: 1. In E/P group, the statistically significants were shown on only mean Y speed in the case of normal standing when eye open (p<.05), but the statistically significants were not shown on mean X, Y speed and velocity moment in the case of normal standing when eye close (p>.05). 2. In control group, the statistically significants were not shown on all posture (p>.05). 3. There was a statistically significant difference on the mean Y speed and velocity moment in the case of normal standing when eye open between control group and E/P group (p<.05). Conclusions: The above results revealed that balance training using Eye movement program were partly effective for improving the static balance ability.