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열 순환 처리가 Gingival shade 복합레진의 기계적 특성에 미치는 영향
임용운,황성식 대한치과기공학회 2017 대한치과기공학회지 Vol.39 No.2
Purpose: The objective of this study was to evaluate influence of mechanical properties of gingival shade composite resins(GSCRs) according to thermocycling treatment. Methods: The material utilized in this study was Crea.lign(CGR), Twiny flow(TGF) and Twiny(TGP). Total sixty specimens were fabricated with a dimension of 25×2×2mm according to the ISO 4049. After fabrications, specimens of before and after thermocycling(to 55℃ from 5℃) were stored in the distilled water for 24 hours at the 37℃. Three-point flexural test was performed in universal testing machine(Instron 5966, USA) at a crosshead speed of 1 mm/min. Flexural strength, flexural modulus and work of fracture according to the thermocycling were analyzed using a one-way ANOVA analysis. Surface analysis of GSCRs after thermocycling evaluated using the scanning electron microscope. Results: : The highest FS was measured in TGP group of NTC group and lowest in CGR group after TC. After TC, FS and FM decreased in CGR and TGP groups, but TGF increased. There was a statistically significant difference between FS and WOF in GSCRs(p <0.05). But FM did not show any significant difference after TC (p> 0.05).The strength of the characteristic exceeded the flexural strength required by ISO 4049(> 80 MPa). Weibull modulus(m) showed the highest reliability in the TGP group (m = 14.22), and the reliability of the TGF and TGP groups after TC decreased. Conclusion: Thermocycling treatment is important factor influence of mechanical properties with gingival shade composite resins. Therefore, we recommended that mechanical properties need to get useful information and accuracy for life-span expectancy according to the thermocycling treatment.
광경화성 3D 프린팅 레진의 출력각도에 따른 굽힘 특성과 신뢰성 평가
임용운,송두빈,황성식,김사학,한만소,Im, Yong-Woon,Song, Doo-Bin,Hwang, Seong-Sig,Kim, Sa-Hak,Han, Man-So 대한치과기공학회 2021 대한치과기공학회지 Vol.43 No.1
Purpose: This study aimed to compare the flexural properties and perform the Weibull analysis of photo-curing three-dimensional (3D) printing resin. Methods: Photo-curing temporary resin (3D polymer) was used as a printing resin. Specimens (65 × 10 × 3.3 ㎣) were prepared following the ISO 20975-1 guidelines and according to the different printing orientations using a digital light processing 3D printer (D2 120; Dentium). The flexural strength (FS), flexural modulus, and work of fracture (WOF) were measured using a universal testing machine (Instron 3344; Instron) at a crosshead speed of 5 mm/min. Results: In this study, the 0° orientation exhibited higher FS and WOF than the 45° orientation. Significant differences were found among the printing orientations (p<0.05). Specimens printed at the 0° orientation were the most accurate. In the Weibull analysis, 0° showed the greatest Weibull modulus (m), which represents a higher reliability. Conclusion: 3D printing should be selected and used by considering flexural properties, size accuracy, and reliability.
임용운,황성식,김사학,최재우,정수하,김시철 대한치과기공학회 2018 대한치과기공학회지 Vol.40 No.1
Purpose: The purpose of this study was to investigate the influence of mechanical properties of various ultra-dental stone by setting methods. Methods: 240 cylinder specimens(10 mm × 20 mm) were prepared from three ultra-dental stones(Gemma, Die keen and Fuji rock; n = 80) in accordance with the manufacturers' recommendations. Half of the specimens of each stone(n= 40) were dried in open air within a room temperature; the other half(n = 40) underwent in a silicone rubber mold in open air for 30 minutes and then were dried in a microwave oven for 10 minutes to 600W. Compressive strength(CS), compressive modulus(CM) and diametral tensile strength(DTS) conducted until fracture using Instron 5966 at each of the following periods: 1 and 24 hours from mixing. One-way analysis of variance and Scheffe's post hoc test were performed for statistical comparisons at a significance level of P<.05. Results: The CS and CM values in all dental stone indicated highest after 24h(54.25 MPa < ) than the values for specimens dried in microwave method . The DTS values revealed the highest microwave method. However, in 24h, FJ(Fu-ji rock) and GM(Gemma) had lower mechanical properties than air. Conclusion : Within the limitations of this study, CS did not influence by microwave method but DTS affected according to the setting.
글레이즈 컬러를 적용한 의치상 레진의 비커스 경도 평가
임용운 대한치과기공학회 2022 대한치과기공학회지 Vol.44 No.3
Purpose: This study was conducted to compare the Vickers hardness on the denture acrylic resins using the glaze color system. Methods: The specimens (20×2 mm) were prepared by mixing according to the manufacturer’s protocols through thermal polymerization and self-polymerization. The surface roughness was measured using a testing machine after water-soaking for 48 hours. For the Vickers hardness measurement, the completed specimen was soaked in water for 48 hours and then applied at 200 gf for 30 seconds. Was the specimen immersed after being soaked in water for 48 hours at temperatures of 5℃ and 55℃, respectively, for 30 seconds for the thermos-cycling treatment, and it was carried out 5,000 times. Results: Surface roughness was higher in the more glazing group than in the control group. A significant difference was observed in all groups, except for the Retec Don 2000 and Luciton 199 groups (p<0.05). As a result of measuring the Vickers hardness, the treatment by glaze color showed slightly lower but the thermo-cycling treatment group appeared higher than control group in all. Conclusion: Therefore, the glaze color was found to affect the surface roughness and showed a significant difference. The surface glaze color showed a very high Vickers hardness after the thermo-cycling treatment, indicating that the surface-strengthening effect is greater in the oral environment.
심미성 향상을 위한 간접수복용 Gum-Shade 복합레진의 굽힘 특성 평가
임용운 ( Yong Woon Im ),황성식 ( Seong Sig Hwang ) 한국치위생과학회 2015 치위생과학회지 Vol.15 No.4
This study investigated flexural properties of indirect Gum-shade composite resins for esthetic improvement. The material utilized in this study was Crea.lign, Twiny flow and Twiny paste (TP). Ten specimens were fabricated with a dimension of 25×2×2 mm according to the ISO 4049. After fabrications, specimens were stored in the distilled water for 24 hours at the temperature of 37oC. Three-point bending test was performed in universal testing machine (Instron 3344; Instron, USA) at a crosshead speed of 1 mm/min until the failure occurred. TP exhibited a higher flexural strength (FS) and flexural modulus (FM) compared to the flowable materials. There were significant differences among the three materials in FS and FM. However, there was no significant difference in work of fracture (WOF) in all tested materials (p>0.05). In Weibull analysis, TP showed the greatest Weibull modulus which means a higher reliability of the materials. Also, Gum-shade composite resins revealed a strong correlation in all flexural properties. There was a positive correlation in FS-FM (r2=0.99) and a negative correlation between FS-WOF and FM-WOF (r2>0.97). Therefore, this confirmed that flexural property was important for mechanical behavior evaluation and useful information. To addition, this improved among mechanical properties correlation of materials as important factor.