• The Journal of Advanced Prosthodontics
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• v.12 no.5
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• pp.259-264
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• 2020

PURPOSE. The aim of this study was to investigate and compare the color stability of provisional restorative materials fabricated by 3D printing, dental milling, and conventional materials. MATERIALS AND METHODS. For the experimental groups, two commercially available 3D-printing provisional resins (E-Dent 100; EnvisionTEC GmbH, Germany & VeroGlaze™; Stratasys^®, USA), two dental milling blocks (PMMA Disk; Yamahachi Dental Co., Japan & Telio^®CAD; Ivoclar Vivadent AG, Liechtenstein), and two conventional materials (Alike™; GC Co., Japan & Luxatemp automix plus; DMG, Germany) were used. The water sorption and solubility test were (n=10, respectively) carried out according to ISO4049:2000 (International Standards Organization, Geneva, Switzerland). For the color stability test (n=10), coffee and black tea were used as staining solutions, and the specimens were stored for 12 weeks. Data were analyzed by one-way ANOVA and Tukey's HSD using SPSS version 22.0 (SPSS Inc. Chicago, IL, USA) (P<.05). RESULTS. Alike and Veroglaze showed the highest values and Luxatemp showed the lowest water sorption. In the color stability test, the ΔE of conventional materials varied depending on the staining solution. PMMA milling blocks showed a relatively low ΔE up to 4 weeks, and then significantly increased after 8 weeks (P<.05). 3D-printed materials exhibited a high ΔE or a significant increase over time (P<.05). CONCLUSION. The degree of discoloration increased with time, and a visually perceptible color difference value (ΔE) was shown regardless of the materials and solutions. PMMA milled and 3D-printed materials showed more rapid change in discoloration after 8 weeks.

• Journal of Technologic Dentistry
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• v.38 no.3
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• pp.135-142
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• 2016

Purpose: The aim of this research was to evaluate the influence of different surface treatments on the shear bond strength of zirconia ceramic to composite resin. Methods: Seventy two cylinder-shape (diameter: 5 mm; height: 12 mm) blocks of experimental industrially manufactured Y-TZP ceramic were abraded with $125{\mu}m\;Al_2O_3$ particles and randomly divided into 4 groups. All the materials were categorized as group Gc(control group - composite resin veneering on zirconia surface), Gr - composite resin veneering after surface treatment of Rocatec system (3M ESPE, Seefeld, Germany) group; Gz - composite resin veneering after surface treatment of Zirconia primer (Z-primer, Bisco, U.S.A) group; Gm - composite resin veneering after surface treatment of zirconia primer (Monobond plus, ivoclar vivadent AG, Liechtenstein) group. Two different zirconia primers and Rocatec system were used to zirconia cylinders (n=16) onto the zirconia surface. Zirconia specimens, polished and roughened, were pretreated and composite bilayer cylinders bonded using conventional adhesive techniques. Results: Shear bond strengths were analyzed using single-factor ANOVA(p<0.05). Bond strength values achieved after airbone particle abrasion and zirconia surface pre-treatments(p<0.05). Conclusion: Shear bond strength tests denmonstrated that zirconia primer is a viable method to improved bond strength between zirconia ceramic core and veneering composites.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.2
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• pp.111-127
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• 2003

Statement of problem : Resin cements were used widely on all ceramic crowns, but the influence of resin cements on biocells was not understood clearly. Purpose : This study was investigated to evaluate the biocompatibility of resin cements for all-ceramic crowns. Material and Method : The resin cements used in this study were Panavia F (Kuraray Co., Ltd. Japan), Variolink II (Vivadent Ets., Schann / Liechtenstein), and Bistite II (Bistite dual cure resin cement-clear Tokuyama Soda Co. Japan). The viability of normal human oral keratocytes, gingival fibroblast, and gingival fibroblast immortalized by Human Papilloma virus 16 was measured in vitro for evaluation of cytotoxicity on resin cements, and the response of pulp tissue was analyzed and evaluated with light microscope after application of cements at cutting edge of incisors. Results : The normal human oral keratocytes was the most sensitive to toxicity of resin cement, and toxicity of cements was higher in Bistite II than in Variolink II. The cell viability of immortalized gingival fibroblast did not affected by type of cement and cultivation period, but there was a tendency that cytotoxicity in Bistite II was higher than in Variolink II. The cell viability of gingival fibroblast was similar to that of immortalized gingival fibroblast regardless of cement type, but Bistite II showed more toxic than others after 5 days cultivation. The responses of pulp tissue according to cement type were similar after 2 days cultivation, but revealed high toxicity in Bistite II after 10 days cultivation. Conclusion : Variolink II was more biocompatible than any other resin cements used in this study.

• The Journal of Advanced Prosthodontics
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• v.7 no.6
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• pp.454-459
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• 2015

PURPOSE. To determine whether the fracture strengths and failure types differed between metal and zirconia frameworks veneered with pressable or layering ceramics. MATERIALS AND METHODS. A phantom molar tooth was prepared and duplicated in 40 cobalt-chromium abutments. Twenty metal (IPS d.SIGN 15, Ivoclar, Vivadent, Schaan, Liechtenstein) and 20 zirconia (IPS e.max ZirCAD, Ivoclar) frameworks were fabricated on the abutments. Each framework group was randomly divided into 2 subgroups according to the veneering material: pressable and layering ceramics (n=10). Forty molar crowns were fabricated, cemented onto the corresponding abutments and then thermocycled ($5-55^{\circ}C$, 10,000 cycles). A load was applied in a universal testing machine until a fracture occurred on the crowns. In addition, failure types were examined using a stereomicroscope. Fracture load data were analyzed using one-way ANOVA and Tukey HSD post-hoc tests at a significance level of 0.05. RESULTS. The highest strength value was seen in metal-pressable (MP) group, whereas zirconia-pressable (ZP) group exhibited the lowest one. Moreover, group MP showed significantly higher fracture loads than group ZP (P=.015) and zirconia-layering (ZL) (P=.038) group. No significant difference in fracture strength was detected between groups MP and ML, and groups ZP and ZL (P>.05). Predominant fracture types were cohesive for metal groups and adhesive for zirconia groups. CONCLUSION. Fracture strength of a restoration with a metal or a zirconia framework was independent of the veneering techniques. However, the pressing technique over metal frameworks resisted significantly higher fracture loads than zirconia frameworks.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.3
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• pp.385-393
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• 1993

Injection processing of denture base resin was introduced by Pryer in 1942, in an attempt to reduce processing shrinkage. More recently a continuous-pressure injection type technique has been developed (SR-Ivocap, Ivoclar AG, Schaan, Liechtenstein.), and it reduced processing error and increased resin density. The purpose of this study was to compare tensile bond strength of heat-cured, cold-cured, and light-cured denture base resin bonded to continuous-pressure injection type resin. To know it, 60 cylindrical resin specimens were fabricated, and tensile bond strength were measured. The results were as follows : 1. The mean tensile bond strength bonded to continuous-pressure injection type resin was lower than bonded to conventional heat cured resin. But tensile bond strength of conventional heat cured resin bonding with light cured resin was lower than continuous-pressure injection type resin. 2. Of the tensile bond strength bonded to continuous-pressure injection type resin, tensile bond strength bonding with continuous-pressure injection type resin was the greatest(but not significantly different from bonding with conventional heat cured resin), followed by cold-cured, light-cured resin. 3. Of the tensile bond strength bonded to conventional heat cured resin, tensile bond strength bonding with conventional heat cured resin was the greatest and followed by continuous-pressure injection type resin, cold-cured resin, light-cured resin. According to these results, bonding of continuous-pressure injection type resin with conventional heat cured resin or continuous-pressure injection type resin is acceptable, but bonding with light-cured resin is questionable.

• The Journal of Advanced Prosthodontics
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• v.13 no.4
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• pp.258-267
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• 2021

PURPOSE. The purpose of this study was to compare the surface roughness, phase transformation, and surface topography of dental zirconia with three different yttrium oxide compositions under same grinding and polishing conditions. MATERIALS AND METHODS. Three zirconia disks (IPS e.max ZirCAD LT, MT, MT multi, Ivoclar Vivadent AG, Schaan, Liechtenstein) were selected for experimental materials. Sixty-nine bar-shaped specimens were fabricated as 12.0 × 6.0 × 4.0 mm using a milling machine and glazing was conducted on 12.0 × 6.0 mm surface by same operator. With a custom polishing device, 12.0 × 6.0 mm surfaces were polished under same condition. Surface roughness (Ra[㎛]) was measured before grinding (C), after grinding (G), and at every 3 steps of polishing (P1, P2, P3). X-ray diffraction and FE-SEM observation was conducted before grinding, after grinding, and after fine polishing (P3). Statistical analysis of surface roughness was performed using Kruskal-Wallis test and Mann-Whitney-U test was used as a post hoc test (α = .05). RESULTS. There were no significant differences of surface roughness between LT, MT, and MM groups. In LT, MT, and MM groups, P3 groups showed significantly lower surface roughness than C groups. X-ray diffraction showed grinding and polishing didn't lead to phase transformation on zirconia surface. In FE-SEM images, growths in grain size of zirconia were observed as yttrium oxide composition increases. CONCLUSION. Polished zirconia surface showed clinically acceptable surface roughness, but difference in yttrium oxide composition had no significant influence on the surface roughness. Therefore, in clinical situation, zirconia polishing burs could be used regardless of yttrium oxide composition.

• Journal of Technologic Dentistry
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• v.41 no.3
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• pp.177-185
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• 2019

Purpose: This study was to investigate the effect of three different surface treatments on the shear bond strength of lithium disilicate ceramics to enamel. Methods: Totally 60 lithium disilicate ceramic disc specimens were fabricated with IPS e.max press (Ivoclar Vivadent, Schaan, Liechtenstein) and Mazic Claro (Vericom, Korea). 30 specimens in each lithium disilicate ceramic were assigned to 3 groups of the each following surface treatment: 1) $50{\mu}m$ airborne particle abrasion+silane, 2) 9.5% hydroflouric acid etching (HF)+silane, 3) $50{\mu}m$ airborne particle abrasion+9.5% HF+silane. Lithium disilicate ceramic surfaces after surface treatments were AFM examined. The shear bond strength was measured in a universal testing machine at 0.5mm/min crosshead speed. All data were analyzed using a two-way ANOVA and Tukey's test(${\alpha}=0.05$). Results: The mean surface roughness of lithium disilicate ceramics ranged from $0.178{\mu}m$ to $0.441{\mu}m$. The mean shear bond strengths ranged from $23.81{\pm}2.78MPa$ to $33.99{\pm}4.85MPa$. Conclusion: 1. Mazic Claro showed higher shear bond strength than IPS e.max press at 3 different surface treatments, and no statistically significant was observed. 2. The shear bond strength of IPS e.max press was strongly enhanced as surface treated with $50{\mu}m$ airborne particle abrasion and 9.5% hydroflouric acid etching. And there was no statistical significance at the shear bond strength of Mazic Claro with surface treatments.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.4
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• pp.273-279
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• 2010

Purpose: The purpose of this in vitro study was to compare the marginal adaptation of a ceramic-pressed-to-metal restoration with traditional metal-ceramic restoration. Materials and methods: Duplicating the prepared resin tooth, 20 metal dies were fabricated. Twenty metal copings of 2 groups which were metal ceramic restoration and pressed to metal restoration were fabricated. The marginal opening of each coping was measured with Microscope (BX 60M-36E $41D^{(R)}$: Olympus, Japan). After porcelain build-up, the marginal opening of metal ceramic restoration and pressed to metal restoration ($PoM^{(R)}$: Ivoclar vivadent., Liechtenstein) were also evaluated in the same method. The measurements were analyzed using Wilcoxon Signed Ranks test and Mann-Whitney U test. Results: Within the limits of this study, the results were as follows. 1. Metal-ceramic restorations in coping state ($64.93{\pm}12.48\;{\mu}m$) in compared with Metal ceramic restorations after porcelain build-up ($63.43{\pm}12.86\;{\mu}m$) had no significant difference in marginal adaptation. 2. Pressed-metal-ceramic restorations in coping state ($50.00{\pm}12.28\;{\mu}m$) in compared with Pressed metal ceramic restorations after porcelain build-up ($56.72{\pm}13.80\;{\mu}m$) had no significant difference in marginal adaptation. 3. Metal-ceramic restorations in compared Pressed-metal-ceramic restorations had no significant difference in marginal adaptation. Conclusion: Pressed-metal-ceramic restorations have the advantage of being technically less change through using of the lost-wax technique and this allows for the convenience of a full-contour ceramic wax-up as opposed to the more technique-sensitive layering method. Pressed-metal-ceramic restorations may be considered in clinic on the basis of the result of this study and the advantage of this system.

• Restorative Dentistry and Endodontics
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• v.35 no.3
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• pp.188-197
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• 2010

The purpose of this study was to compare radiopacity and radiographic discriminability of various FRC-Posts. Six FRC-Posts were investigated ; 1) FRC Postec Plus (Ivoclar Vivadent AG, Schaan, Liechtenstein), 2) Snowlight (Carbotech, Lewis center, OH, USA), 3) Dentin Post (Komet Brasseler, Lamgo, Germany), 4) Rely-X Fiber Post (3M ESPE, St.paul, MN, USA), 5) D.T.-Light Post (BISCO, Schaumburg, IL,USA), 6) Luxapost (DMG, Hamburg, Germany) The radiographs of each post with a reference 1 mm / 2 mm aluminum step-wedge was taken using digital sensor. The optical density were calculated by gray value of $10{\times}10$ pixel and compared in mm Al equivalent at five points. Six maxillary incisors of similar radiopacity were used. Radiographs of posts in Mx. incisors of lingual side of dry mandible were taken. We showed radiographs and asked the questionnaire to 3 radiologists, 3 endodontists, 3 general practitioners. The questionnaire was comprised of choices of the highest, lowest radiopaque individual post and the choices of best discriminable post at apical, coronal area. The following results were obtained. 1. Each post system showed various radiopacity. 2. There was change of discriminability between each post and simulated specimens regardless of examiner. Although each post showed various radiopacity, the difference of radiopacity did not affect on discriminability.

• Restorative Dentistry and Endodontics
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• v.30 no.3
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• pp.158-169
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• 2005

This study was done to evaluate the shear bond strength between light-cured glass ionomer cement (GIC) base and resin cement for luting indirect resin inlay and to observe bonding aspects which is produced at the interface between them by SEM. Two types of light cured GIC (Fuji II LC Improved, GC Co. Tokyo, Japan and Vitrebond$^{TM}$, 3M, Paul Minnesota U.S.A) were used in this study. For shear bond test, GIC specimens were made and immersed in 37$^{\circ}C$ distilled water for 1 hour, 24 hours, 1 week and 2 weeks. Eighty resin inlays were prepared with Artglass$^{(R)}$ (Heraeus Kultzer Germany) and luted with Variolink$^{(R)}$ II (Ivoclar Vivadent, Liechtenstein). Shear bond strength of each specimen was measured and fractured surface were examined. Statistical analysis was done with one-way ANOVA. Twenty four extracted human third molars were selected and Class II cavities were prepared and GIC based at axiopulpal lineangle. The specimens were immersed in 37$^{\circ}C$ distilled water for 1 hour, 24 hours, 1 week and 2 weeks. And then the resin inlays were luted to prepared teeth. The specimens were sectioned vertically with low speed saw. The bonding aspect of the specimens were observed by SEM (JSM-5400$^{(R)}$, Jeol, Tokyo, Japan) .There was no significant difference between the shear bond strength according to storage periods of light cured GIC base. And cohesive failure was mostly appeared in GIC On scanning electron micrograph, about 30 - 120 $\mu$m of the gaps were observed on the interface between GIC base and dentin. No gaps were observed on the interface between GTC and resin inlay.