• The Journal of Advanced Prosthodontics
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• v.13 no.3
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• pp.144-151
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• 2021

PURPOSE. The purpose of this in vitro study was to investigate the wear resistance and surface roughness of three interim resin materials, which were subjected to chewing simulation. MATERIALS AND METHODS. Three interim resin materials were evaluated: (1) three-dimensional (3D) printed (digital light processing type), (2) computer-aided design and computer-aided manufacturing (CAD/CAM) milled, and (3) conventional polymethyl methacrylate interim resin materials. A total of 48 substrate specimens were prepared. The specimens were divided into two subgroups and subjected to 30,000 or 60,000 cycles of chewing simulation (n = 8). The wear volume loss and surface roughness of the materials were compared. Statistical analysis was performed using one-way analysis of variance and Tukey's post-hoc test (α=.05). RESULTS. The mean ± standard deviation values of wear volume loss (in mm³) against the metal abrader after 60,000 cycles were 0.10 ± 0.01 for the 3D printed resin, 0.21 ± 0.02 for the milled resin, and 0.44 ± 0.01 for the conventional resin. Statistically significant differences among volume losses were found in the order of 3D printed, milled, and conventional interim materials (P<.001). After 60,000 cycles of simulated chewing, the mean surface roughness (Ra; ㎛) values for 3D printed, milled, and conventional materials were 0.59 ± 0.06, 1.27 ± 0.49, and 1.64 ± 0.44, respectively. A significant difference was found in the Ra value between 3D printed and conventional materials (P=.01). CONCLUSION. The interim restorative materials for additive and subtractive manufacturing digital technologies exhibited less wear volume loss than the conventional interim resin. The 3D printed interim restorative material showed a smoother surface than the conventional interim material after simulated chewing.

• International Journal of CAD/CAM
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• v.8 no.1
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• pp.41-44
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• 2009

This paper describes an implementation of virtual teeth modeling for a haptic dental simulation. The system allows dental students to practice dental procedures with realistic tactual feelings. The system requires fast and stable haptic rendering and volume modeling techniques working on the virtual tooth. In our implementation, a volumetric implicit surface is used for intuitive shape modification without topological constraints and haptic rendering. The volumetric implicit surface is generated from input geometric model by using a closest point transformation algorithm. And for visual rendering, we apply an adaptive polygonization method to convert volumetric teeth model to geometric model. We improve our previous system using new octree design to save memory requirement while increase the performance and visual quality.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.293-302
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• 2020

The purpose of this study was to evaluate the applicability of virtual reality simulation after experience of dental caries diagnosis for dental students before exposing to clinical pediatric practice. A pediatric patient model of a five-year-old child with primary dentition was developed and a caries model that is amenable to VR(virtual reality) diagnosis was organized and set-up. The dental student's were allowed to use the simulated model for fifteen minutes and their experiences were evaluated using a self-reported questionnaire to evaluate presence and usability of this application. Overall, virtual presence and appearance area of the simulation were highly scored. The result indicates that the VR model has no significant difference from the actual clinical caries regardless of grade of students, gender and VR experience. If the prototype is continuously advanced, its applicability in dental education will increase.

• The Journal of the Korea Contents Association
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• v.21 no.8
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• pp.258-270
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• 2021

This study aimed to investigate the effects of the virtual reality simulation for malocclusion examination for dental education. A 4-step modeling procedure was applied to develop a tooth model with a realistic level in order to be held and observed in detail. Eighty-six participants used HMDs to examine the developed virtual dental simulation to identify their perception according to expertise levels. The independent variable, expertise group, included three levels: 29 juniors, 29 seniors, and 28 dentists, respectively. The dependent variables, that were task-load and usability, were measured through two cases. Results showed that the junior group perceived a higher level of mental demands and embarrassment than the dentist group. It indicated that the perceived task load varies according to the expertise levels in the simulation task. However, the senior group perceived a higher level of ease of use than the dentist group. This study presented the implications for the development of virtual reality simulation in detail.

• Journal of International Society for Simulation Surgery
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• v.3 no.2
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• pp.90-92
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• 2016

Horizontal bone defect in the anterior maxilla makes it difficult to place dental implant. The golden standard for bone augmentation is autogenous block bone graft. Tight contact with recipient site and rigid fixation are two key factors for successful block bone graft. Ramal bone graft has been the most reliable methods for dental implant field. However, the curvature of the alveolar ridge is different from ramal bone shape. Intraoperative trimming of ramal bone is cumbersome for surgeon. In this technical note, a simple way to design the ramal bone harvest using bone wax stent is reviewed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.321-323
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• 2004

We developed the monte-carlo simulation code for analysis of the On signal in dental medium. In calculation, we obtain the two different propagation signals as a function of the probing depth. Signal 2 begins to exceed the signal 1 at a very small probing depth(=60${\mu}{\textrm}{m}$). For reduce the signal, detection area is limited to radius and detection angle. As numerical result, probing depth becomes appoximately 500${\mu}{\textrm}{m}$.

• Journal of Drive and Control
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• v.20 no.1
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• pp.27-33
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• 2023

From the perspective of dental chair manufacturers, it is important to of localizing hydraulic system in order to secure market competitiveness. This study aims to develop the analysis model of a dental chair which overseas companies secure core technologies. The study follows the steps below. First, the component parts of the solenoid valve unit of a foreign leading company are analyzed and implemented in virtual environment. Second, dynamic behavior scenario is established based on solenoid valve signal chart provided by a foreign leading company. The analysis model is verified and its performance is analyzed using dynamic behavior according to each scenario. Third, a simulation is carried out to determine whether the cylinder velocity of designed hydraulic system surpasses 1cm/s as required by the design.

• Journal of Drive and Control
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• v.20 no.2
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• pp.1-6
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• 2023

This study aims to develop a Korean dental chair hydraulic circuit by improving the existing equipment in order to localize foreign leading companies' products. The suggested Hydraulic circuit can be applicable to varied sectors where height and backrest angle control of chair-type equipment are required. The study followed the steps below. First, three kinds of foreign hydraulic circuits were analyzed and three kinds of Korean dental chair hydraulic circuits were suggested. Second, it was determined whether the three kinds of Korean hydraulic circuits operate normally through SimulationX, a software specialized in multi domain analysis, and the effectiveness of each circuit was examined.

• Journal of Drive and Control
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• v.20 no.4
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• pp.35-44
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• 2023

This study aimed to analyze the performance of hydraulic systems for dental chair when long working hours makes the temperature of hydraulic fluid rise. The study was carried out in the following manner. First, 'cylinder's clearance' was reflected in the three kinds of hydraulic circuits, which were developed through the preceding study, in order to analyze oil leak. Second, 12 cases of simulations comprised of the up and down of cylinders were carried out. Third, it was determined whether the cylinder velocity of dental chair surpasses 1cm/s required in the development even in the hydraulic fluid temperature of 60℃. In conclusion, this study used SimulationX to verify the performance stability at high temperatures using three types of hydraulic circuits designed to develop a Korean unit chair.

• Journal of International Society for Simulation Surgery
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• v.2 no.2
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• pp.76-79
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• 2015

One of the most serious complications after head and neck radiation is osteoradionecrosis (ORN) of the jaw. The etiology of ORN is extraction, minor dental procedure or dental implant surgery. When ORN of the jaw progressed to stage III, free fibular flap is the most useful methods for reconstruction. In this case report, a 67-year-old ORN patient who underwent fibular free flap reconstruction using simulation surgery with 3-dimensional rapid prototype (3D RP) model was reviewed. After partial mandibulectomy, a osteocutaneous fibula flap was used for reconstruction. Oro-cutaneous fistula was resolved after operation. Patients reported improved food intake after operation without pus discharge. Functional and esthetic results showed successful reconstruction.