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    Effect of Er:YAG laser pulse duration on repair bond strength of resin-based and hybrid CAD/CAM restorative materials
    (Taylor & Francis Ltd, 2022) Bayraktar, Yusuf; Demirtag, Zulfikar; Celik, Cigdem
    Besides the output power and pulse frequency, the pulse duration of Er:YAG laser is an important parameter for conditioning the restorative material surface. This study aimed to investigate the effect of six different pulse modes of Er:YAG laser on the repair bond strength of a hybrid ceramic and two resin-based CAD/CAM restorative materials. Twenty-eight specimens (5 x 5 x 4 mm) were prepared for each CAD/CAM block (Lava Ultimate-(LU), Vita Enamic-(VE), and GC Cerasmart-(GCC)) and randomly divided into seven groups. The specimens except the control group were irradiated using Er:YAG laser at 3 W and 20 Hz using quantum square pulse (QSP), super short pulse (SSP), short pulse (SP), medium short pulse (MSP), long pulse (LP), and a very long pulse (VLP). A micro-hybrid resin composite (Filtek Z250, 3 M ESPE, USA) was placed up to 4 mm on each CAD/CAM specimen in two increments. Bar specimens (1 x 1 x 8 mm) were obtained using a cutting device and thermocycled 10,000 times at 5-55 degrees C. Microtensile bond strength (mu TBS) test was performed at a 1 mm/min crosshead speed. Data were statistically analyzed using two-way ANOVA and Tukey's HSD tests (p < 0.05). mu TBS was significantly affected by both pulse duration and material type (p < 0.001). Pulse duration and material type showed a statistically significant interaction (p < 0.001). Except for QSP, shorter pulse modes resulted in a higher repair bond strength. VLP mode is not recommended to be used in repair procedures with the materials tested.
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    Öğe
    Effect of femtosecond laser beam angle on bond strength of zirconia-resin cement
    (Springer London Ltd, 2015) Akpinar, Yusuf Z.; Kepceoglu, Abdullah; Yavuz, Tevfik; Aslan, Muhammed A.; Demirtag, Zulfikar; Kilic, Hamdi S.; Usumez, Aslihan
    Yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic is widely used as an all-ceramic core material because of its enhanced mechanical and aesthetic properties. The bond strength of Y-TZP restorations affects long-term success; hence, surface treatment is required on ceramic boundaries. This study evaluated the effect of different laser beam angles on Y-TZP-resin cement shear bond strength (SBS). Forty plates of Y-TZP ceramics were randomly assigned to four groups (n = 10). A femtosecond amplifier laser pulse was applied on Y-TZP surface with different incidence angles (90A degrees, 75A degrees, 60A degrees, 45A degrees). The resin cement was adhered onto the zirconia surfaces. The SBS of each sample was measured using universal testing machine at crosshead speed of 1 mm/min. The SBS was analyzed through one-way analysis of variance (ANOVA)/Tukey tests. The results showed that the degree of laser beam angle affects the SBS of resin cement to Y-TZP. The laser beam was applied to a surface with a 45A degrees angle which resulted in significantly higher SBS (18.2 A +/- 1.43 MPa) than other groups (at 90A degrees angulation (10.79 A +/- 1.8 MPa), at 75A degrees (13.48 A +/- 1.2 MPa) and at 60A degrees (15.85 A +/- 0.81 MPa); p < 0.001). This study shows that decreasing of the angle between the ceramic surface and the laser beam increased the SBS between the resin cement and the ceramic material, as well as the orifice.
  • [ X ]
    Öğe
    A Survey on Prevalence, Causes and Prevention of Post-cementation Hypersensitivity
    (Dennis Barber Ltd, 2016) Demirtag, Zulfikar; Uzgur, Recep; Turkal, Mustafa; Uzgur, Zeynep; Colak, Hakan; Ozcan, Mutlu
    This study evaluated the prevalence and causes of post-cementation sensitivity and possible prevention measures according to the experience of dentists through an inter-net survey. A questionnaire was prepared with 25 items based on a survey introduced by Rosenstiel and Rashid. An online site was created for the participation to the survey. A total of 322 participants responded the questionnaire. The results of the questionnaire indicated the amount of tooth preparation (42.1%) is the most frequent reason for hypersensitivity followed by water-cooling with pressure (11.2%) and provisionals (10.9%). "Very important" response for tooth reduction, time before cementation, overheating, luting agent, occlusion and provisionals were found to be of statistical significance (p<0.001). Comparing respondents' opinions the incidence of post-cementation sensitivity appears to be underestimated. Tooth reduction, preparation under high volume spray and quality of provisional restorations was considered to have a significant impact on the incidence of post-cementation sensitivity according to the dentists surveyed across Turkey. Respondents to the questionnaire considered the use of antimicrobial, desensitizing, resin bonding, hemostatic agents, varnishes, type of liner material, rotary instruments to be less effective for prevention of post-cementation sensitivity.