• 한국정밀공학회지
• /
• 제28권8호
• /
• pp.915-928
• /
• 2011

Titanium for dental implant application has the superior properties of biocompatibility, specific strength, and corrosion resistance. However, it is extremely difficult to find a suitable surface treatment method for sufficient osseointegration with biological tissue/bone cell and implant surface. Surface treatment technology using laser has been researched as the way to increase surface area of implant. In this study, to develop the surface treatment process with improved adhesion between implant and bone cell at the same time for superior biocompatibility, pulsed laser beam was overlapped continuously for scribed surface morphology and determination of friction coefficient. As the results, surface area and friction coefficient was increased over 2 times by the comparison with sand blasting, which is used for the conventional method. In this time, the optimal condition for laser beam power and beam irradiation speed was 13 watt and 50 mm/sec, respectively.

• 대한치과기공학회지
• /
• 제45권2호
• /
• pp.31-38
• /
• 2023

Purpose: This in vitro study aimed to compare the trueness of 3-unit fixed dental provisional prostheses (FDPs) fabricated by three different additive manufacturing and subtractive manufacturing procedures. Methods: A reference model with a maxillary left second premolar and the second molar prepped and the first molar missing was scanned for the fabrication of 3-unit FDPs. An anatomically shaped 3-unit FDP was designed on computer-aided design software. 10 FDPs were fabricated by subtractive (MI group) and additive manufacturing (stereolithography: SL group, digital light processing: DL group, liquid crystal displays: LC group) methods, respectively (N=40). All FDPs were scanned and exported to the standard triangulated language file. A three-dimensional analysis program measured the discrepancy of the internal, margin, and pontic base area. As for the comparison among manufacturing procedures, the Kruskal-Wallis test and the Mann-Whitney test with Bonferroni correction were evaluated statistically. Results: Regarding the internal area, the root mean square (RMS) value of the 3-unit FDPs was the lowest in the MI group (31.79±6.39 ㎛) and the highest in the SL group (69.34±29.88 ㎛; p=0.001). In the marginal area, those of the 3-unit FDPs were the lowest in the LC group (25.39±4.36 ㎛) and the highest in the SL group (48.94±18.98 ㎛; p=0.001). In the pontic base area, those of the 3-unit FDPs were the lowest in the LC group (8.72±2.74 ㎛) and the highest in the DL group (20.75±2.03 ㎛; p=0.001). Conclusion: A statistically significant difference was observed in the RMS mean values of all the groups. However, in comparison to the subtractive manufacturing method, all measurement areas of 3-unit FDPs fabricated by three different additive manufacturing methods are within a clinically acceptable range.

• 한국표면공학회지
• /
• 제41권5호
• /
• pp.226-231
• /
• 2008

Titanium and its alloy have been widely used in dental implant and orthopedic prostheses. Electrochemical characteristics of dental implant in the various simulated body fluids have been researched by using electrochemical methods. Ti-6Al-4V alloy implant was used for corrosion test in 0.9% NaCl, artificial saliva and simulated body fluids. The surface morphology was observed using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The electrochemical stability was investigated using potentiosat (EG&G Co, 263A). The corrosion surface was observed using scanning electron microscopy (SEM). From the results of potentiodynamic test in various solution, the current density of implant tested in SBF and AS solution was lower than that of implant tested in 0.9% NaCl solution. From the results of passive film stability test, the variation of current density at constant 250 mV showed the consistent with time in the case of implant tested in SBF and AS solution, whereas, the current density at constant 250mV in the case of implant tested in 0.9% NaCl solution showed higher compared to SBF and AS solution as time increased. From the results of cyclic potentiodynamic test, the pitting potential and |$E_{pit}\;-\;E_{corr}$| of implant tested in SBF and AS solution were higher than those of implant tested in 0.9% NaCl solution.

• The Journal of Advanced Prosthodontics
• /
• 제6권6호
• /
• pp.468-473
• /
• 2014

PURPOSE. This study aimed to evaluate the accuracy of digitizing dental impressions of abutment teeth using a white light scanner and to compare the findings among teeth types. MATERIALS AND METHODS. To assess precision, impressions of the canine, premolar, and molar prepared to receive all-ceramic crowns were repeatedly scanned to obtain five sets of 3-D data (STL files). Point clouds were compared and error sizes were measured (n=10 per type). Next, to evaluate trueness, impressions of teeth were rotated by $10^{\circ}-20^{\circ}$ and scanned. The obtained data were compared with the first set of data for precision assessment, and the error sizes were measured (n=5 per type). The Kruskal-Wallis test was performed to evaluate precision and trueness among three teeth types, and post-hoc comparisons were performed using the Mann-Whitney U test with Bonferroni correction (${\alpha}=.05$). RESULTS. Precision discrepancies for the canine, premolar, and molar were $3.7{\mu}m$, $3.2{\mu}m$, and $7.3{\mu}m$, respectively, indicating the poorest precision for the molar (P<.001). Trueness discrepancies for teeth types were $6.2{\mu}m$, $11.2{\mu}m$, and $21.8{\mu}m$, respectively, indicating the poorest trueness for the molar (P=.007). CONCLUSION. In respect to accuracy the molar showed the largest discrepancies compared with the canine and premolar. Digitizing of dental impressions of abutment teeth using a white light scanner was assessed to be a highly accurate method and provided discrepancy values in a clinically acceptable range. Further study is needed to improve digitizing performance of white light scanning in axial wall.

• 폴리머
• /
• 제29권1호
• /
• pp.102-105
• /
• 2005

다양한 치아 수복이 가능한 광중합형의 치아수복용 고분자 나노복합체(polymeric dental restorative nanocomposites, PDRNC)를 제조하고 이들의 심미적 물성을 고찰하였다. PDRNC 제조에 사용한 충전제는 평균 입경이 1${\mu}m$인 바륨실리케이트와 40 nm 및 7 nm 크기의 나노실리카를 혼성화시켜 사용하였는데 bisphenol A glycerolate methacrylate와 triethyleneglycol dimethacrylate (60/40 wt%)으로 구성되는 기재와의 혼화성 증가를 위해 실란으로 표면을 소수성으로 처리하였다. 가시광선을 이용한 PDRNC의 광중합에 필요한 광개시제는 camphorquinone을, 광증감제는 2-(dimethylamino)ethyl methacrylate을 사용하였다. 제조된 PDRNC의 심미적 물성을 Hunter L, a, b 값으로 평가한 결과, 7nm 크기의 나노 충전제가 첨가될수록 PDRNC의 투명성이 증가되어 심미적 특성이 향상됨을 알 수 있었다.

• 대한치과의사협회지
• /
• 제40권2호통권393호
• /
• pp.107-117
• /
• 2002

• The Journal of Advanced Prosthodontics
• /
• 제9권2호
• /
• pp.85-92
• /
• 2017

PURPOSE. The aim of this study was to evaluate the effect of tooth surface pre-treatment steps on shear bond strength, which is essential for understanding the adhesive cementation process. MATERIALS AND METHODS. Shear bond strengths of different cements with various tooth surface treatments (none, etching, priming, or etching and priming) on enamel and dentin of human teeth were measured using the Swiss shear test design. Three adhesives (Permaflo DC, Panavia F 2.0, and Panavia V5) and one self-adhesive cement (Panavia SA plus) were included in this study. The interface of the cement and the tooth surface with the different pre-treatments was analyzed using SEM. pH values of the cements and primers were measured. RESULTS. The highest bond strength values for all cements were achieved with etching and primer on enamel ($25.6{\pm}5.3-32.3{\pm}10.4MPa$). On dentin, etching and priming produced the highest bond strength values for all cements ($8.6{\pm}2.9-11.7{\pm}3.5MPa$) except for Panavia V5, which achieved significantly higher bond strengths when pre-treated with primer only ($15.3{\pm}4.1MPa$). Shear bond strength values were correlated with the micro-retentive surface topography of enamel and the tag length on dentin except for Panavia V5, which revealed the highest bond strength with primer application only without etching, resulting in short but sturdy tags. CONCLUSION. The highest bond strength can be achieved for Panavia F 2.0, Permaflo DC, and Panavia SA plus when the tooth substrate is previously etched and the respective primer is applied. The new cement Panavia V5 displayed low technique-sensitivity and attained significantly higher adhesion of all tested cements to dentin when only primer was applied.

• Composites Research
• /
• 제30권6호
• /
• pp.393-398
• /
• 2017

손상된 치아의 복구에 사용되는 재료인 치과용 복합레진 Clearfil AP-X (Kuraray, Japan)을 대상으로 디지털 이미지 상관법을 이용하여 광중합 시 발생하는 수축분포를 관찰하였다. 디지털 이미지 상관분석법을 위해, CCD 카메라를 이용하여 광조사 중과 광조사 이후의 촬영 조건을 달리하여 사진을 획득하였다. 광조사중의 최적의 촬영 조건을 설정하기 위하여 노출시간을 0.15 ms부터 0.55 ms까지 0.05 ms 간격으로 촬영한 사전 실험을 통해 촬영 조건을 획득하였다. DIC 분석 결과 복합레진의 비균일한 수축 분포를 관찰하였으며 복합레진의 중심 부분에서 시편의 계면부보다 좀 더 자유로운 유동성으로 더 큰 수축이 발생하였다. 복합레진의 중합수축은 초기 20 s 의 광조사에서 최종경화수축률의 50~60% 수준까지 발생하였다. 이러한 치과용 복합레진의 큰 수축량은 레진/기질계면 근처에서 인장응력이 집중하도록 영향을 주었다.

• 대한치과기공학회지
• /
• 제34권3호
• /
• pp.227-235
• /
• 2012

Purpose: This study compared the surface hardness (Vickers) and microstructural characteristics between a type IV stone with and without die hardening treatment, a polyurethane die material. Methods: Materials used were a type IV stone(MG Crystal Rock), two die hardeners (Hardening bath, Epox-it), and a polyurethane resin material(Polyluck). Six specimens per group were prepared according to manufacturer's directions. The prepared specimens were tested by means of hardness test, one-way ANOVA analysis, scanning electron microscopic(SEM) observations and energy dispersive spectroscopic(EDS) analysis. Results: In the hardness test and its statistical analysis, there was no significant difference in the surface hardness between a type IV stone and type IV stone with die hardener coating, type IV stone mixed with an epoxy like material instead of water. In contrast, polyurethane resin material exhibited significantly greater surface hardness than other specimen groups (p<0.05). Conclusion: By considering the results of the hardness test, SEM observations and EDS analysis, although the die hardeners on type IV stone did not show remarkable improvement in surface hardness, the die hardener coating on the surface of type IV stone material did show decrease of microporous and improvement of surface defects.

• 융합신호처리학회논문지
• /
• 제20권1호
• /
• pp.37-44
• /
• 2019

유년기에서 성장기인 어린이들의 조기 치아 관리가 중요시 되고 있으며 어린이 환자 치과 진료도 꾸준히 증가하는 추세이다. 치과 치료에 불안을 느끼는 어린이 환자의 긴장을 완화시켜주기 위한 다양한 진정 요법이 요구되고 있다. 본 논문에서는 레진 치료에 쓰이는 치료 기구의 사용 상태를 실시간으로 파악하여, 사용 중인 치료 기구와 치료 단계에 따라 다른 스토리와 효과를 가진 애니메이션을 생성 할 수 있는 상호작용 시스템의 개발 내용에 대해 기술한다. 애니메이션은 주인공 캐릭터와 악당인 충치 캐릭터가 전투를 벌여 진료 단계에 맞춰 주인공 캐릭터가 악당을 하나씩 무찔러 승리하는 스토리이며, 치료 시작 시 재생되며 치료가 끝나면 애니메이션도 동시에 종료된다. 현재 어린이 치과에서 서비스되는 기존의 애니메이션 시청은 일방적으로 애니메이션이 재생되기만 할 뿐 어린이의 시선을 이끌기에는 부족함이 있다. 환자의 치료 과정에 맞추어 애니메이션 흐름이 진행된다면 어린이에게 색다른 흥미를 주어 치료에 대한 긴장감이 좀 더 완화될 것이다.