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Bonding performance and fracture strength of resin-infiltrated zirconia blocks for CAD/CAM systems
김사학,김재홍,김종견,김욱태 대한치과기공학회 2016 대한치과기공학회지 Vol.38 No.4
This study aimed to investigate the influence of hybrid technology on the biaxial flexural strength of conventional ceramic materials and to evaluate whether polymer addition to zirconia more effective bonding than hybridization in glass-ceramics against resin cement. Two conventional ceramics[Vita PM9(GC) and I-JAM(ZC)] and two hybrid ceramics[CELTRA Duo(ZRC) and Vita Enamic(RIZ)] were evaluated. Each group of materials were selected for quantitative bonding performance evaluation and the biaxial flexural strength, and then debonded surfaces were inspected with scanning electron microscopy(SEM). Data were analyzed by a one-way ANOVA test, followed by Tukey’s HSD test(α=0.05). The RIZ group had a significantly higher bond strength than the other groups(p<0.05). ZC showed the lowest mean bond strength values. SEM micrographs showed a sand-blasted ZC surface, whereas RIZ showed an undulation because of the fracture of the bodies of substrate. The flexural strength of ZC was significantly higher than those of all other ceramics evaluated. The flexural strength of RIZ was significantly lower than those of GC, ZRC, and ZC, whereas no significant difference was observed between GC and ZRC Ceramic hybridization with polymers is one of the essential strategies to enhance the bond strength of CAD/CAM ceramics to resin cement. Not all hybrid ceramics display the same quality of bonding performance; however RIZ have lower mechanical strength when tested with the biaxial bending method.
석고계(石膏系) 및 인산염계(燐酸鹽系) 매몰재의 Liquid 온도에 따른 주조체 적합도에 관한 실험적 연구
김사학,Kim, Sa-Hak 대한치과기공학회 1996 대한치과기공학회지 Vol.18 No.1
Among investment for dental casting, we selected 4 kinds of investment(2 Gypsum-bonded and 2 Phosphate-bonded) and prepard 120 specimen by dividing into two cast of using Ring and Ringless case from $0^{\circ}C$ to $30^{\circ}C$ at interval of $10^{\circ}C$ to invest in fluence on the fitness of casting body according to the liquid temperature of Gypsum-bonded and Phosphate-bonded investment. The result was as follows; 1. Gypsum-bonded investment showed best fitness at $30^{\circ}C$ representing difference of singnificance in order of $20^{\circ}C$, $10^{\circ}C$, and $0^{\circ}C$, From the difference of investment, Deguvest was proved superior than Cristobalite. 2. Phosphate-bonded investment showed no severe difference at $10^{\circ}C$ and $20^{\circ}C$, but showed better fitness at $10^{\circ}C$, representing difference of significance in order of $0^{\circ}C$, $30^{\circ}C$, difference of significance was shown between investment also. 3. In Ringless investing method, there were no difference of significance in Deguvest CF and Unovest. 4. When using a Ring with a Sheet of asbestos liner installed, there was some difference of significance representing superiority of Ringless investing method.
김사학,Kim, Sa-Hak 대한치과기공학회 2011 대한치과기공학회지 Vol.33 No.4
Purpose: This study was conducted to examine the phase transition according to the zirconia surface treatment. Methods: The specimens were divided to four groups. The first group was sintered at $1,500^{\circ}C$ and ground; the second group was sintered at $700^{\circ}C$, ground, and sintered at $1,500^{\circ}C$; the third group was sintered at $1,500^{\circ}C$, ground, and $110{\mu}m$-sandblasted; and the fourth group was sintered at $1,500^{\circ}C$, ground, $110{\mu}m$-sandblasted, treated with 9.5% hydrofluoric acid, and ultrasonic cleaner-washed for two minutes. The monoclinic fractions were measured, and the surface was observed via SEM. Results: The monoclinic fraction was $0.13{\pm}0.19%$ in the control group Zr1, $1.91{\pm}0.15%$ in the experimental group Zr2, $7.71{\pm}0.34%$ in Zr3, and $8.39{\pm}0.25%$ in Zr4. On the surface, the phase transition hardly occurred in the control group Zr1, but it increasingly occurred in the experimental groups Zr3 and Zr4. Conclusion: The monoclinic fraction was high in the experimental groups Zr3 and Zr4. The phase transition did not occur in the control group, but increasingly occurred in the experimental groups.
도재전장관용 Opaque 도재에 관한 연구 - paste opaque을 중심으로 -
김사학,고대진,이용근,김광만,김경남,Kim, Sa-Hak,Ko, Dae-Jin,Lee, Yong-Keun,Kim, Kwang-Mahn,Kim, Kyoung-Nam 대한치과기공학회 2002 대한치과기공학회지 Vol.23 No.2
The purpose of this study was to analyze the commercial paste opaque products currently available in domestic of foreign as well as domestic, such as Duceram Plus(DU; Ducera Dental GmbH, Germany), VMK 95(VM; Vita Co., Germany), Noritake EX-3(EX; Noritake Co., Japan) and Ceramax(CE; Alphadent Co., Korea). They were characterized in thermal expansion coefficient, particle size distribution, viscosity and solvent using thermomechanical analyzer, particle size analyzer, rheometer and infrared spectrophotometer. Experimental results are as follows; Firstly, thermal expansion coefficients were determined $13.9{\times}10-6/^{\circ}C$ for DU, $14.3{\times}10-6/^{\circ}C$ for VM, $13.3{\times}10-6/^{\circ}C$ for EX, and $14.0{\times}10-6/^{\circ}C$ for CE. Secondly, percent of partice size below $1{\mu}m$ were 12% for DU, VM and CE, and 13% for EX, percent between $1{\mu}m$ and $5{\mu}m$ were 42% for DU, 42% for VM, 38% for EX, and 61 % for CE, percent between $5{\mu}m$ and $10{\mu}m$ were 21 % for DU, 24% for VM, 20% for EX, and 18% for CE, and over $10{\mu}m$ were 25% for DU, 22% for VM, 29% for EX, 9% for CE. Thirdly, the basic composition of the solvent in all of the commercial paste opaques were determined as ethylene glycol from FT-IR investigation. Lastly, measured viscosities were 1798 cp for DU, 536 cp for VM, 1110 cp for EX, and 721 cp for CE.