• Ceramist
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• v.7 no.1
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• pp.11-20
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• 2004

오늘날 고령화와 사고의 증가 및 삶의 질이 향상됨에 따라 생체재료에 대한 관심과 수요는 매우 커지고 있다. 오래전부터 인체의 손상된 부위를 자가이식(autograft)이나 동물을 통한 이종이식(allograft)으로 일부 대체 하였지만, 그 수요와 쓰임에는 많은 한계가 있었다. 생체재료 (biomaterials)는 사고나 질병에 의해 손상된 인체의 조직이나 장기를 대체하거나 그 기능을 회복하기 위해 사용되는 재료를 말한다. 1) 생체재료로서 세라믹스(생체 세라믹스 bioceramics)는 1970년대부터 일부 임플란트 (implant)용으로 쓰이기 시작했으며 현재는 치과(dentistry)및 정형외과(orthopaedics) 분야에서 그 쓰임과 규모는 실로 막대하다. 최근에 생명공학(biotechnology)의 발달과 더불어 생체재료나 조직공학(tissue engineering) 분야가 새롭게 대두되면서, 생체세라믹스를 개발하고자 하는 노력은 선진국을 중심으로 이루어지며, 국내에서도 관심이 집중되고 있다.(중략)

• The Journal of the Korean dental association
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• v.19 no.1 s.140
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• pp.73-80
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• 1981

치과임상에 있어서 약제, 재료, 기구 및 기타 부대시설과 치료실 환경은 오랫동안에 걸쳐 현금에 와서 놀라운 발전을 이룩하였음에도 치과의사가 시술중 받게되는 위해의 가능서은 아직도 여러곳에 상존하고 있는 실정이다. 의사가 늘 갖고 또 자신이 느껴야 되는 책임감에서 오는 긴장, 기계에서 오는 소음이 미치는 신체적영향 특히 청력과 관계되는 점 및 각종약제의 부작용 및 중독증, 그리고 치료중 예기치 않게 발생될 수 있는 환자로 부터오는 각종 감염, 도한 치과의사의 특수한 치료자세로부터 생기는 습관적인 정형외과적 문제와 정신적 육체적으로 겪게되는 격무로부터 오는 전신피로등의 문제를 어쩔수 없이 또는 치과의사 자신의 부주의로 당하고 있는 실례가 많다. 저자는 이 점에 대하여 위해가 생기는 문제를 항목별로 기술하면서 문헌적 고찰과 말레이시아의 치과의사 164명으로부터 설문을 통하여 수집한 사실의 통계를 분류하여 정리하고 그 예방 및 개선의 방법을 제시하면서 이는 치과의사뿐 아니라 종사자 전원이 숙지하여야 할 사실로 강조하였으며 가장 이상적인 치료실내의 치과의사용 의자를 고안하고 그 구조에 대하여 설명 하였다.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.93-97
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• 2003

Using alumina-glass infiltrated material which has been in the spotlight of biomaterials including dental material, appropriate composition of glass infiltrated material mainly depends on the thermal expansion coefficient. To obtain proper compositional glass of suitable thermal expansion coefficient effiiently. a Taguchi analysis was conducted. The influence of alkali oxide and alkali earths oxide, which affect mostly the thermal expansion coefficient of glass infiltrated material, was infiltrated material, the effect having influenced on the thermal expansion coefficient of glass was presented in this order (Na$_2$O≫K$_2$O ≫MgO≒CaO). The effect of Na$_2$O was about eight times as great as the effects of MgO, CaO and $K_2$O was about four times. Among the interaction affects of each variables the interaction affects of $K_2$O-CaO showed most significantly and thermal expansion property of specified composition was predicted by calculating contribution rate on each level of variables and interaction affects.

• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.359-367
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• 2019

For this study, specimens were prepared using five types of composite resin and resin-reinforced glass ionomer Fuji II LC, and 29 days precipitation was done in four kinds of solution, which were soy sauce, gochujang, wine, and distilled water. Ten specimens for each coloring sample were divided into two groups, one those surfaces was polyester film and the other with 1200-grit abrasive paper, and 20 specimens per materials. Color change (${\Delta}{\ast}ab$) in the colored specimens is measured in 2days, 7days, 14days and 29days using spectrophotometer (CM-2600d, Konica, Minolta, Ramsey, NJ). All values were considered significant when P<0.05. 1. Each material is discolored over time under the influence of different storage solutions. 2. In soy source, among the specimens polished with polyester film, color change was observed in resin-modified glass ionomer Fuji II LC, prodigy and compomer F-2000 on day 2. Meanwhile, Fuji II LC showed noticeable color change in specimens prepared with 1200-grit sandpaper on day 2, which was followed by flowable resin on day 7. 3. On day 2, there was a color change with the specimens of flowable resin, resin-modified glass ionomer Fuji II LC and Prodigy among the hybrid specimen in the groups of polyester film in gochujang.

• Korean Journal of Dental Materials
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• v.44 no.4
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• pp.329-336
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• 2017

This study evaluates the machining accuracy of the custom abutment design according to the selected convergence angle and radius of curvature value in the CAD program. Ten custom abutments were designed based on dental CAD. And then, the fabricated custom abutment was scanned ten times using a contact scanner. The data of the scanned custom abutment was saved as "Test STL" file. The Geomagic studio software was used to superposition each exported as an "Test STL" file with the CAD-reference-model STL file (CRM) specified by the same name. In the experimental results, the A8 group (convergence angle $8^{\circ}$) showed lower error than the A4 group (convergence angle $4^{\circ}$) . In addition, the higher the radius of curvature, the less error in the top and chamfer regions of the custom abutment (p< 0.05). Overall, the convergence angle and radius of curvature value in the custom abutment design were found to affect the machining accuracy.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.274-279
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• 2016

Purpose: The purpose of this study was to evaluate the transmission of candida in denture by dental polishing lathe. Materials and Methods: Maxillary complete dentures made from the same model were infected with Candida albicans. Polishing wheels were keep in various chlorhexidine solution and distilled water for an hour. The infected dentures were polished by prepared dental polishing lathe with sterile pumice and distilled water. And then sterile maxillary complete dentures were polished with same method. Polishing surface was wiped with a cotton swab and the sample was regrown for checking Candida albicans. Results: All polishing wheel with chlorhexidine resist fungal infection. But the polishing wheel with distilled water is infected with Candida albicans. Conclusion: A chlorhexidine is highly efficient in fungal infection prevention on dental polishing lathe.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.2
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• pp.217-228
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• 2023

This study aimed to compare the physical properties of 4 kinds of calcium silicate-based cements (CSCs): 2 kinds of powder-liquid mix type (RetroMTA^® [RTMX] and Endocem^® MTA Zr [EZMX]) and 2 kinds of premixed type (Well-Root^TMPT [WRPR] and Endocem^® MTA premixed [ECPR]) CSCs, respectively. Further, we assessed the setting times, solubility values, and compressive strengths of the cements. The shortest setting time was observed for EZMX (123.33 ± 5.77 seconds), followed by RTMX (146.67 ± 5.77 seconds), ECPR (260.00 ± 17.32 seconds), and WRPR (460.00 ± 17.32 seconds), respectively. The highest solubility was observed for WRPR (9.01 ± 0.55%), followed by RTMX (2.17 ± 0.07%), EZMX (0.55 ± 0.03%), and ECPR (0.17 ± 0.03%). Furthermore, the highest compressive strength was observed for ECPR (76.67 ± 25.67 Mpa), followed by WRPR (38.39 ± 7.25 Mpa), RTMX (35.07 ± 5.34 Mpa), and EZMX (4.07 ± 0.60 Mpa). In conclusion, the premixed type CSCs (WRPR and ECPR) exhibited longer setting times compared to the powder-liquid mix type CSCs (EZMX and RTMX). The solubility test showed that ECPR had the lowest solubility while WRPR had the highest solubility, with a statistically significant difference between them (p < 0.0083). Additionally, the compressive strength test showed that ECPR had the highest compressive strength, while EZMX had the lowest compressive strength, also with a statistically significant difference between them (p < 0.0083). ECPR is a promising material as it is premixed, eliminating the need for mixing time, and it has also demonstrated improved solubility and compressive strength, making it a potentially favorable option for clinical use.

• Korean Journal of Dental Materials
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• v.44 no.3
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• pp.273-280
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• 2017

The aim of the present study was to investigate the effects of specimen dimension on the flexural properties and testing reliability of dental composite resin. The composite resin was prepared experimentally by mixing a resin matrix with silanated micrometer glass filler at 50 vol%. Flexural specimens with various dimension in specimen's width were fabricated by light curing using a split metal mold; $25{\times}2{\times}2mm$, $25{\times}2{\times}4mm$, $25{\times}2{\times}6mm$ in length ${\times}$ height ${\times}$ width. The flexural strength and modulus were determined according to ISO 4049 test protocol at a span length of 20 mm (normal-flexural strength; NFS). Another flexural test was conducted using mini-sized specimens ($12{\times}2{\times}2mm$, $12{\times}2{\times}4mm$, $12{\times}2{\times}6mm$) from the broken specimens at a span length of 10 mm (mini-flexural strength; MFS). Data were analyzed with ANOVA and Duncan's post-hoc test and the test reliability was evaluated by Weibull analysis. Results showed that there are generally no significant difference in flexural strength with the increase in the specimen width in NFS and MFS tests. However, the test reliability of flexural strength based on Weibull analysis was largely changed with the variables in the dimension of width and span length. The flexural modulus of NFS was increased as the dimension of specimens width increased while there was no trend in flexural modulus of MFS test. Overall results recommend that the evaluation of flexural properties and the reliability of dental composite resins should be performed with more than one test method.

• Journal of Biomedical Engineering Research
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• v.20 no.6
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• pp.539-546
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• 1999

현재 상용화되고 있는 치과용 76.5% Pd-11.2% Cu-7.2% GarP 합금의 왁스모형을 원심주조기로 주조하여, 임상조건의 탈개스 및 세라믹 소성처리를 하였다. 이에따른 각각의 시편에 대해 미세조직의 변화를 주사전자현미경 및 EDS로 관찰하고, 최종적인 투과전자현미경으로 조사하였다. 각 조건의 편석, 결정립계 및 석출물부위를 주사전자현미경과 EDS 고 관찰한 결과, 이원계 Pd-GA합금의 안정상들에 해당하는 정량적인 조성비는, 단지 상대적으로 Ga의 성분비만 높게 감지되었다. 특히, 세라믹소성 처리후 미세조직에서 형성된 석출물에 근접한 기지조직일수록 Ga의 농도가 상대적으로 줄어든 고갈현상을 확인하엿다. 또한 투과전자현미경의 제한시야회절도형 분석결과, 주조 및 탈개스처리 후 미세조직의 편석부위에서는 GA의 가장 큰 강도를 보였고, 또 Ga과 Pd 고용체 사이에 미세한 판상의 석출물에 기인하는 줄무늬를 관찰하였다. 한편, 세라믹소성처리후 미세조직의 석출물은 금속간화합물 Pd2Ga으로 밝혀졌으며, 기지조직은 <100> 방향을 따라 약 25nm의 폭을 가지는 미세한 섬유상 형태의 소위 "tweed 조직'을 형성하였다.성하였다.

• Korean Journal of Dental Materials
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• v.44 no.1
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• pp.69-77
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• 2017

The aim of this study was to investigate the effects of chitosan powder addition on the strengthening of conventional glass ionomer cement. Two types of chitosan powders with different molecular weight were mixed with conventional glass ionomer cement (GIC): low-molecular weight chitosan (CL; 50~190 kDa), high-molecular weight chitosan (CH; 310~375 kDa). The chitosan powders (CL and CH) were separately added into the GIC liquid (0.25-0.5 wt%) under magnetic stirring, or mixed with the GIC powder by ball-milling for 24 h using zirconia balls. The mixing ratio of prepared cement was 2:1 for powder to liquid. Net setting time of cements was measured by ISO 9917-1. The specimens for the compressive strength (CS; $4{\times}6mm$), diametral tensile strength (DTS; $6{\times}4mm$), three-point flexure (FS; $2{\times}2{\times}25mm$) with flexure modulus (FM) were obtained from cements at 1, 7, and 14 days after storing in distilled water at $(37{\pm}1)^{\circ}C$. All mechanical strength tests were conducted with a cross-head speed of 1 mm/min. Data were statistically analyzed by one-way ANOVA and Tukey HSD post-hoc test. The mechanical properties of conventional glass ionomer cement was significantly enhanced by addition of 0.5 wt% CL to cement liquid (CS, DTS), or by addition of 10 wt% CH (FS) to cement powder. The CL particles incorporated into the set cement were firmly bonded to the GIC matrix (SEM). Within the limitation of this study, the results indicated that chitosan powders can be successfully added to enhance the mechanical properties of conventional GIC.