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Öğe Atomic force microscopy investigation of lithium disilicate glass ceramic after various surface treatments(TAYLOR & FRANCIS LTD, 2014) Kara, H. B.; Kara, O.; Sayin, G.; Cakan, U.; Ozturk, A. N.The aim of this study is to evaluate the influence of various surface treatments on the surface roughness of a lithium disilicate glass ceramic. A total of 25 discs of lithium disilicate glass ceramic were prepared. Specimens were divided into five groups: (1) no treatment, (2) air abrasion, (3) acid etching, (4) Nd:YAG laser irradiation and (5) Er:YAG laser irradiation. Digital images from the surfaces were obtained by means of an atomic force microscope in tapping mode. Surface roughness was measured in 10x10 mu m boxes. Surface roughness data were analysed by one way analysis of variance. The air abrasion group (550 +/- 212 nm) had a significantly higher mean surface roughness value than the other groups. The acid etching group (392 +/- 157 nm) had a significantly higher mean roughness value than the control group (228 +/- 105 nm). Surface roughness of lithium disilicate glass ceramic was not increased by any of the laser irradiation treatments.Öğe Bond strength of resin composite to light activated bleached enamel(WOLTERS KLUWER MEDKNOW PUBLICATIONS, 2016) Yavuz, T.; Ozyilmaz, O. Y.; Ozturk, A. N.; Aykent, F.Objectives: This study evaluated the microtensile bond strength (mu TBS) of a resin composite bonded to bleached enamel as a function of bleaching conditions. Materials and Methods: The whiteness hydrogen peroxide (HP) bleaching agent containing 35% HP was applied to the central incisors' facial enamel surface and irradiated as follows: No treatment (G1; control); no light (G2); light-emitting diode, the 40s (G3); diode laser, the 20s (G4); and neodymium: yttrium aluminum garnet laser, 20s (G5). A Variolink II resin composite structure was then built up incrementally on the surface. The teeth were sectioned into three 1.2 mm x 1.2 mm wide "I"-shaped sections. The specimens were then subjected to microtensile testing at a crosshead speed of 1 mm/min. Data were analyzed using one-way ANOVA (alpha = 0.05) followed by the Tukey Honestly Significant Difference post-hoc test. The fractured surfaces were observed with a stereomicroscope at x 100 magnification. Results: One-way ANOVA revealed no statistical differences among the groups (P > 0.05). No differences appeared between the groups bonded 14 days after bleaching (P > 0.05). Mean mu TBS values (MPa) were as follows: 22.05 +/- 5.01 (G1); 19.6 +/- 5.6 (G2); 19.3 +/- 5.4 (G3); 20.08 +/- 2.08 (G4); and 18.1 +/- 4.8 (G5). Many adhesive failures occurred at the bleached and irradiated enamel surfaces. Conclusion: The various irradiation treatments following the application of the whiteness HP bleaching agent to enamel did not significantly reduce the mu TBS within a 14-day period.Öğe Sealing properties of four different post systems.(INT AMER ASSOC DENTAL RESEARCHI A D R/A A D R, 2003) Ozturk, A. N.; Usumez, A.; Cobankara, F. Kont; Eskitascioglu, G.; Belli, S.[Abstract not Available]