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    Effect of ultrashort pulsed laser on bond strength of Y-TZP zirconia ceramic to tooth surfaces
    (Japanese Soc Dental Materials Devices, 2015) Unal, Server Mutluay; Nigiz, Remzi; Polat, Zelal Seyfioglu; Usumez, Aslihan
    There is limited knowledge about the effects of ultrashort pulsed laser on zirconia ceramic surfaces. The aim of this study was to evaluate the effects of ytterbium (Yb)-doped fiber laser and other surface treatment methods -namely, sandblasting with 110 mu m aluminum oxide or 30 mu m silica-coated alumina on shear bond strength (SBS) of zirconia to tooth surface. A total of 128 zirconium oxide disks were made by using CAD-CAM technology. Disk surfaces were sandblasted with Al2O3 particles or silica-coated alumina or irradiated with Yb-doped fiber based nanosecond pulsed laser at 85W output power at 25 kHz. Disks were luted to dentin using two different resin cement. SBS of each specimen was measured. Results were statistically analyzed using two-way analysis of variance (ANOVA) and Bonferroni and Dunnett tests (p<0.005). Highest bond strength was obtained when zirconia surface was pretreated with Yb-doped fiber-based nanosecond pulsed laser regardless of the resin cement used.
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    Öğe
    The Effect of Ytterbium-Doped Fiber Laser with Different Parameters on Physical Properties of Zirconia Surface
    (Mary Ann Liebert, Inc, 2017) Unal, Server Mutluay; Ozkir, Serhat Emre; Polat, Zelal Seyfioglu; Guven, Sedat; Asutay, Hilal
    Objective: Laser irradiation is an alternative surface treatment method for roughening zirconia surfaces. The aim of this study was to evaluate the effects of ytterbium-doped fiber laser (YbPL) on zirconia. Background: Zirconia surfaces are resistant to many surface treatment methods, but surface roughness is crucial for adhesion of veneering materials and cements to zirconia. Methods: The zirconia discs were prepared and divided into four groups according to the power of the laser irradiation (5, 12, 17, and 20W). These groups were divided into five subgroups according to the frequency (25, 40, 60, 80, and 100kHz). Surface roughness values were measured with a noncontact profilometer, and the mean Ra values were calculated. Wettability was measured with a goniometer. The surface morphology was observed with a scanning electron microscope (SEM). The changes in the surface crystalline structure were analyzed with X-ray diffractometry. Results: Ra values of all groups were higher than the control group. The highest surface roughness value was at 20W and 100kHz. Best wettability characteristic was observed at 5W and 60kHz. The correlations between Ra and wettability were low but significant. SEM examination of 5W with different frequencies showed no microcracks, however, melted areas were observed. Remaining groups had microcracks and melted layers. A significantly lower T/M-phase transformation was observed in some groups. Conclusions: YbPL irradiation was effective at roughening the zirconia surface. Although laser treatment affected zirconia surfaces and provided surface roughness, the power and frequency should be adjusted to achieve optimum results.
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    Evaluation of Bond Strength of Different Repair Methods Applied in PEEK Infrastructure Restorations
    (Sci Printers & Publ Inc, 2021) Yilmaz, Berivan Dundar; Cetinkaya, Numan; Polat, Zelal Seyfioglu; Unal, Server Mutluay; Tuncer, Mehmet Cudi
    OBJECTIVE: To evaluate the appropriate intraoral repair procedures in PEEK (polyetheretherketone) restorations when there is a veneer fracture. STUDY DESIGN: The study groups were formed according to the presence or absence of fractured veneer material of PEEK restorations. PEEK specimens (N = 91) were prepared with CAD/CAM in dimensions of 5 x 5.4 x 13 mm and divided into 13 groups including the positive control group. 5000 thermocyclic was applied to the specimens, and then the repair bond strength (RBS) was made at a speed of 0.5 mm/min. The fracture surfaces of the specimens were examined under a stereomicroscope. SEM, EDX, XRD, AFM, and surface contact angle analyses were performed in terms of roughened surfaces of PEEK (N = 16). One-way ANOVA and independent sample t test were used for data analysis (alpha = 0.05). RESULTS: The efficiency of surface treatment, the roughness and wettability of the acid and Co-Jet groups have increased. Acid etching was found to be the most effective surface treatment. The RBS values of the Super-Bond groups in the repair procedures were found to be higher than the Visio.link group and were statistically significant (p = 0.002). When evaluating failure modes, the mode most encountered among all groups was the mixed mode, and least was the cohesive mode. CONCLUSION: The presence or absence of fractured veneer during the repair of PEEK-based restorations does not affect the values of repair bond strength, and RBS values were also not statistically significant.