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Öğe Bond strength of adhesively luted ceramic discs to different core materials(WILEY, 2009) Bozogullari, Nalan; Inan, Ozgur; Usumez, AslihanThe purpose of this in vitro study was to compare the shear bond strengths of resin, glass-ionomer, and ceramic-based core materials to all ceramic discs. Five core materials (Core max, Sankin; Clearfil AP-X, Kuraray; Empress Cosmo, Ivoclar-Vivadent; Photocore, Kuraray; Dyract Extra, Dentsply) were prepared as discs 10 mm in diameter and 2 mm in height according to the manufacturer's instructions. Ten disc specimens per group were prepared, and dentin served as the control. All resin specimens were embedded in autopolymerizing acrylic resin, with one surface facing up. All ceramic discs (IPS Empress I, Ivoclar-Vivadent) 3 mm in diameter and 2 mm in height were prepared and bonded to core specimens with a dual-curing luting resin cement (Variolink II, Vivadent). Specimens were stored in distilled water at 37 degrees C. Shear bond strength of each sample was measured after 24 h using a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed with one-way analysis of variance and Tukey HSD tests (alpha=0.05). Shear bond strength varied significantly depending on the core material used (p<0.05). Clearfil AP-X and Photocore showed the highest shear bond strength value while Empress Cosmo provided the lowest (p<0.05). There were no statistically significant differences among Clearfil AP-X, Photocore, and Core-Max (p>0.05). And also there were no statistically significant differences between Dyract Extra and the control group (p>0.05). In vitro shear bond strengths of ceramic discs bonded to resin-based core materials showed higher bond strength values than ceramic-based core material. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 89A: 466-471, 2009Öğe The effect of ceramic thickness and number of firings on the color of ceramic systems: An in vitro study(MOSBY-ELSEVIER, 2007) Uludag, Bullent; Usumez, Aslihan; Sahin, Volkan; Eser, Kursat; Ercoban, ErtugrulStatement of problem. Although all-ceramic restorations are widely used, there is a lack of information on how color is affected by fabrication procedures. Color matching problems may be encountered in a definitive restoration despite careful shade selection. Purpose. The aim of this study was to evaluate the effect of dentin ceramic thickness and repeated firings on the color of glass-in filtrated aluminum-oxide (In-Ceram) and leucite-reinforced (IPS Empress) all-ceramic systems using a colorimeter. Material and methods. Twenty-one disc-shaped specimens, 10 mm in diameter with a 0.6-mm core thickness and 0.5-, 1-, or 1.5-mm dentin ceramic thickness, were made from each of 2 ceramic systems (n = 7). Repeated firings were performed for each group, and the color differences were compared with the color after the initial firing. Color differences among ceramic specimens were measured using a colorimeter (XL-20 Colorimeter), and data were expressed in Commission Internationale d'Eclairage (CIE) LA-B system coordinates. Repeated-measures analysis of variance was used to analyze the data (number of firings, ceramic brand, and ceramic thickness) for significant differences. The Tukey honestly significant difference test and paired 2-tailed tests were used to perform multiple comparisons (alpha = .05). Results. The L*a*b* values of ceramic systems were affected by the number of firings (3, 5, or 7) (P < .01) and ceramic brand (In-ceram or IPS Empress) (P < .01). L* and a* values were affected by ceramic thickness (0.5, 1, or 1.5 mm) (P < .01); however, b* value was not affected by ceramic thickness (P = .075). Significant interactions were present in L*, a*, b* values between number of firings and ceramic brand (P < .01), and between ceramic brand and ceramic thickness (P < .05). Significant interactions were present between number of firings and ceramic thickness (P < .01) in L* and b* values but not in the a* value (P = .379). Conclusion. The analysis revealed that there were substantial changes in L*a*b* color data as the number of firings increased, which resulted in perceptual color changes in L*a*b* color parameters.Öğe The effects of water flow rate on shear bond strength of self etch resin cement to dentin surface after Er, Cr: YSGG laser etching(TAYLOR & FRANCIS LTD, 2017) Kurt, Aysegul; Yilanci, Hilal; Yondem, Isa; Usumez, AslihanThe aim of the present study was to evaluate the effect of water flow rate on the morphological features of dentin and shear bond strength (SBS) of self-etching resin cement after Er, Cr: YSGG laser etching. Dentin specimens obtained from extracted human third molars were randomly assigned to four groups (n = 23), including one that received no laser irradiation (control-group D) and three others with different laser parameters: 2.25 W, 50 Hz, 60% air with water flow rates of 19 mL/min-100% water (group A), 2.25 W, 50 Hz, 6.75 mL/min-50% water (group B), and 2.25 W, and 50 Hz, 2.75 mL/min-25% water (group C). The morphological features of each group were examined with scanning electron microscopy and atomic force microscopy. The SBS of resin cement disks (Panavia F2.0, Kuraray; Tokyo, Japan) (3 mm in diameter and 2 mm in height) to the dentin specimens was measured using a universal testing machine at a cross head speed of 0.5 mm/min. Bond strength values were analyzed with one-way ANOVA/Tukey tests. There were no significant differences between the SBS values of groups A and B (p > 0.05). However, the SBS values of these groups were significantly higher when compared to groups C and D (p < 0.001). Er, Cr: YSGG laser application with water flow rates of 6.75 or 19 mL/min resulted in better dentin surface alterations and increased the SBS of self-etching resin cement to dentin.Öğe In vivo heat transfer capacities of autopolymerizing, heat-polymerizing, and injection-molded acrylic resins(QUINTESSENCE PUBLISHING CO INC, 2006) Oruc, Selcuk; Usumez, Aslihan; Enhos, Dilek Simsek; Ozturk, NilgunThe aim of this pilot study was to measure the heat transfer capacities of heat-polymerizing, injection-molded, and auto polymerizing acrylic resins in vivo. Two volunteers used acrylic resin removable plates and consumed hot (69 degrees C) and cold drinks (6 degrees C). Differences between oral temperature and highest and lowest temperature readings were recorded. Temperature changes for the autopolymerizing acrylic resin were found to be significantly higher than the heat-polymerizing and injection-molded acrylic resins for both cold and hot drinks. Despite the disadvantages of auto polymerizing acrylic resins, their high heat transfer capacity may be an advantage.Öğe Temperature rise under normal and caries-affected primary tooth dentin disks during polymerization of adhesives and resin-containing dental materials(JAPANESE SOC DENTAL MATERIALS DEVICES, 2008) Tosun, Gul; Usumez, Aslihan; Yondem, Isa; Sener, YagmurThe purpose of this study was to compare the temperature rise under normal and caries-affected primary tooth dentin during photopolymerization of two adhesives and resin-containing restorative materials. Caries-affected and normal dentin disks were prepared from extracted primary molars with only mesial or distal approximal caries (4 mm in diameter, 1 mm in height). Temperature rise during photopolymerization of adhesive materials was measured with a J-type thermocouple wire that was connected to a data logger. Data were analyzed with two-way ANOVA and independent samples t-test. Temperature rise under caries-affected primary tooth dentin disks was higher than that of normal primary tooth dentin disks during polymerization of both adhesive systems and resin-containing dental materials (p<0.05). It was found that adhesive systems induced a higher temperature rise during polymerization as compared to the resin-containing restorative materials (p<0.05). In particular, temperature rise during polymerization of adhesive materials exceeded 5.5 degrees C under caries-affected primary tooth dentin.
