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Öğe Bond strength of resin composite to light activated bleached enamel(Wolters Kluwer Medknow Publications, 2016) Yavuz, Tevfik; Özyılmaz, Özgün Yusuf; Öztürk, Atiye Nilgun; Aykent, FilizObjectives: 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 Effect of mucosa thicknesses on stress distribution of implant-supported overdentures under unilateral loading: Photoelastic analysis(SAGE Publications, 2019) Özyılmaz, Özgün Yusuf; Aykent, Filiz; Sayın Özel, GülsümIntroduction: The aim of this study was to evaluate the effect of different heights of attachment and mucosa thicknesses on the stress distribution of two implant-retained mandibular overdenture designs under loading using the photoelastic stress analysis method. Materials and methods: Six photoelastic models of an edentulous mandibula were fabricated with two solitary implants that were placed in the canine regions. The attachment systems studied were ball and locator stud attachments. Both the ball and locator groups included three models that had different residual ridge heights so as to provide different mucosa thicknesses (1 mm-1 mm, 1 mm-2 mm, 1 mm-4 mm). A static vertical force of 135 N was applied unilaterally (each on the right then the left side) to the central fossa of the first molars. Models were positioned in the field of a circular polariscope to observe the distribution of isochromatic fringes around the implants and the interimplant areas under loading. The photoelastic stress fringes were monitored and recorded photographically. Results: The ball attachment groups showed higher stress values than did the locator groups under loading. Both attachment systems produced the lowest stress values in stimulated 1 mm-1 mm mucosa thickness models. The models with 1 mm-2 mm mucosa thicknesses showed higher stress values than did other models for both attachment systems. The highest stress value observed around both attachment systems was the moderate level in all test models. Conclusion: In different height mucosa thicknesses, locator attachment models distributed the load to the other side of the implant and its surrounding tissue, whereas the ball attachment did not. Regardless of mucosal thickness and attachment type, the implant on the loading side was subjected to the highest stress concentration.Öğe Effect of two activated bleaching techniques on surface roughness of different esthetic restorative materials(Cumhuriyet University Faculty of Dentistry, 2017) Alptekin, Tuncay; Özyılmaz, Özgün Yusuf; Aykent, Filiz; Kara, Haluk BarışObjectives: The aim of this in vitro study was to evaluate surface roughness of six different restorative materials during office bleaching procedures with blue light emitted diode (LED) and diode laser photo activation. Materials and Methods: Filtek TM supreme, Tetric Evo Ceram, Tescera ATL, Clearfill Majesty Esthetic, Durafill VS and IPS Empress 2 materials were evaluated in this study. Twenty specimens, 10 mm in diameter and 2 mm thick, were fabricated from each material using a teflon mold. All specimens were randomly assigned to two groups (n=10). Group 1 received two topical applications of 35% hydrogen peroxide for 20 s. And was photoactivated using LED. Group 2 received topical application of 46% hydrogen peroxide using diode laser. Surface roughness values were measured prior to and following bleaching procedures by using a profilometer. Data were analyzed statistically, by one-way-analysis of variance (ANOVA), post-hoc Tamhane's T2 and independent t tests. Results: Surface roughness values for all restorative materials tested increased after both bleaching procedures (p < 0.05). Tescera ATL bleached with diode laser photo activation showed higher surface roughness value than LED activation (p < 0.05). However, there were no significant differences in two bleaching methods for other restorative materials (p > 0.05). Conclusions: Although clinical effects depend on in-vivo conditions, the effects of office bleaching agents should be known and applied cautiously when a colored restoration is bleached or a restoration is neighboured with the tooth bleached.Öğe Effect of two light activated in-office bleaching agents on microhardness of different esthetic restorative materials(Selcuk University, 2018) Özyılmaz, Özgün Yusuf; Alptekin, Tuncay; Aykent, Filiz; Kara, Haluk BarışBackground: Irradiation sources have been used to reduce the total in-office bleaching time. However, little is known about the effects of the light irradiation bleaching systems on the restorative materials. This in vitro study evaluated the microhardness of 6 different restorative materials during office bleaching procedures with blue light emitted diode and diode laser photoactivation. Methods: FiltekTM supreme (nanofilled), Tetric EvoCeram (nanohybrid), Tescera ATL (ormocer), Clearfill Majesty Esthetic (nanofilled), Durafill VS (microfilled) and IPS Empress II (ceramic) restorative materials were selected in this study. Twenty specimens, 10 mm in diameter and 2 mm thick, were fabricated from each material using a Teflon mold. All specimens were randomly assigned to two groups (n=10). Group 1 received two topical applications of 35% hydrogen peroxide and was photoactivated using blue light emitted diode for 20s. Group 2 received topical application of 46% hydrogen peroxide using diode laser for 30s. Baseline and after bleaching microhardness measurements were taken with a Vickers hardness tester that was used with a 300 g for the porcelain and 100 g for the composite and ormocer specimens, the dwell time was 30 s for all groups. Data were analyzed statistically, with one-way-analysis of variance (ANOVA), post-hoc Tamhane's T2 and independent t tests. Results: After application of both office bleaching agents, microhardness of all restorative materials tested were significantly decreased (p<.05). However, Tetric EvoCeram composite resin material showed the least microhardness value (p<.05). Conclusion: Blue light emitted diode and diode laser activation hydrogen peroxide office bleaching agents have similar effects on the reduction of microhardness of restorative materials. The data of this study revealed that after bleaching, nanofilled (FS, CME), microfilled (Df) specimens demonstrated lower changes in microhardness values than nanohybrid (TEC) composite material.Öğe Management of restricted mouth opening caused by radiation: A clinical report(Mosby-Elsevier, 2016) Özdere, Eda; Sayın Özel, Gülsüm; Aykent, FilizTrismus, a commonly observed sequela in patients who have undergone radiation therapy to treat malignancies of the head and neck, causes a loss of function that reduces patients' overall quality of life. Radiation can cause intense fibrosis in the masticatory muscles, and this fibrosis may lead to trismus. This clinical report describes the management of a patient with radiation-induced trismus who was treated with a custom-made mouth-opening device. The device had maxillary and mandibular sections, was made of a thermoactive acrylic resin material, and was connected with 2 vertical screws in the right and left canine regions. The screws were adjusted daily to increase the oral opening, such that each turn of the screws increased the opening by 0.25 mm. With the help of this device, at the end of a 4-month follow-up period, the patient's maximal interdental distance had increased from 7.16 mm to 19.50 mm. The intraoral opening device described in this study is useful for achieving a vertical opening sufficient to perform dental treatment.Öğe Temperature rises during tooth bleaching with different light-curing units(Taylor and Francis, 2015) Özyılmaz, Özgün Yusuf; Yavuz, Tevfik; Sarı, Tu?rul; Aykent, Filiz; Öztürk, Atiye NilgünThe aim of this study was to evaluate the influence of three different light-curing units on the temperature rise induced in the pulpal cavity, when bleached with 35% hydrogen peroxide (HP). Forty extracted maxillary central incisors were randomly divided into four groups according to photoactivation procedure (n=10). Whiteness HP (WHP) bleaching agent which contains 35% HP bleach was placed on the facial tooth surface and no photoactivation device was used (control); an blue light-emitting diode (LED, 40s), a diode laser (4W, Continous mode, 20s), and Nd:YAG laser (4W, 60Hz frequency, 20s). Temperature rise in the pulpal chamber was measured with a J-type thermocouple wire that was connected to a data logger before and immediately after each 20-40s application. One tooth of each group was selected for scanning electron microscope analysis. Data were analyzed using one-way ANOVA followed by the Games Howell post hoc test at a preset alpha of 0.05. One-way ANOVA revealed that there was a significant difference among the light-curing units (p<0.05) and between control group and light-curing units (p<0.05). The Nd:YAG induced significantly, which resulted in higher temperature increase than other light-curing units (10.7 degrees C). The LED unit produced the lowest temperature changes (3.2 degrees C) among the light-curing units. The presence of the bleaching gel did not cause a temperature increase in control group (0 degrees C). The results suggested that using light-curing units caused temperature changes in the intrapulpal cavity during tooth bleaching. The use of LED will be more safer for pulpal health when assisted with WHP bleaching gel.Öğe The effect of bleaching agents on the color stability of ceromer and porcelain restorative materials in vitro(2013) Kara, Haluk Barış; Aykent, Filiz; Öztürk, BoraThe aim of this in vitro study was to determine the color changes of five different restorative materials after exposing these materials to two different home bleaching agents. This study applied bleaching agents to an ultralow-fusing porcelain, a low-fusing porcelain, two types of heat-pressed glass ceramics, and a ceromer. A total of 24 disc-shaped specimens were fabricated (with a diameter of 10 mm and a thickness of 2 mm) from each material (n=12). The initial color measurements were taken with a spectrophotometer. The first set of specimens were bleached with 10% hydrogen peroxide (HP) for one hour daily for 10 days. The other set of specimens were bleached with 10% carbamide peroxide (CP) bleaching gel for eight hours daily for 14 days. Data were analyzed with the one-way analysis of variance and Kruskal-Wallis statistical test. The difference in the prebleaching and postbleaching color of each material was considered to be statistically significant at p < 0.05. The study found a statistically significant difference among the color changes of the test groups after exposing them to both bleaching agents (p<0.05). Appreciable color change was observed in the Estenia (?E=3.99) specimens that were bleached with the HP, and noticeable color changes were observed in the Estenia (?E=1.89) and IPS Empress 2 (?E=1.66) groups when they were treated with the CP. Restorations (especially polymer-containing restorative materials) should be protected before any bleaching procedure due to the high risk of color change.
