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    Evaluation of the shear bond strength of zirconia to a self-adhesive resin cement after different surface treatment
    (Wroclaw Medical Univ, 2021) Akar, Turker; Dundar, Ayse; Kirmali, Omer; Ustun, Ozlem; Kapdan, Alper; Er, Hakan; Kustarci, Alper
    Background. Bond stability between zirconia and a self-adhesive resin cement is a major concern, and only limited evidence about its longevity is currently available. Moreover, no study has yet comprehensively evaluated the influence of different power levels of the neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser irradiation on the shear bond strength (SBS) of zirconia to a self-adhesive resin cement. Objectives. The aim of this study was to evaluate the SBS of pre-sintered and sintered zirconia to a selfadhesive resin cement after various treatment (air abrasion and the Nd:YAG laser irradiation at varying power levels -1 W, 2 W and 3 W). Material and methods. Ninety-nine zirconia specimens were prepared and divided into 3 groups: control (with no surface treatment); and pre-sintered and sintered groups with surface treatment. Surface treatment was applied before sintering in the pre-sintered group and after sintering in the sintered group. After following all protocols, a resin cement was layered on the zirconia surface. Shear bond strength was measured using a universal testing machine. The results were subjected to the statistical analysis. The surface topography and phase transformation of zirconia were evaluated using the atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses after surface treatment. Results. The laser irradiation (3 W, 1 W and 2 W) of the pre-sintered zirconia surface resulted in the highest SBS values (p < 0.001), while the lowest SBS values were obtained with airborne particle abrasion of the pre-sintered and sintered zirconia surfaces. Conclusions. Laser irradiation increased the SBS of pre-sintered zirconia to a resin cement. Surface treatment with air abrasion had a lesser effect on the SBS values.
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    Evaluation of Various Pretreatments to Fiber Post on the Push-out Bond Strength of Root Canal Dentin
    (ELSEVIER SCIENCE INC, 2017) Kirmali, Omer; Ustun, Ozlem; Kapdan, Alper; Kustarci, Alper
    Introduction: The aim of this in vitro study was to compare the effect of different pretreatments (fiber post) with the laser-activated irrigation (LAI) technique (for removal of the smear layer) on root canal dentin in terms of push-out bond strength (PBS) in a fiber post. Methods: Fifty freshly extracted mandibular single-rooted premolars were prepared, and LAI was applied to all roots (17% EDTA was 5 mL for 120 seconds with an erbium, chromium:yttrium-scandium-galliumgarnet laser [0.50 W, 20 Hz, 25 m1]). In addition, 50 quartz fiber posts were randomly assigned to 5 groups (n = 10) according to the surface treatments as follows: group S (sandblasting), group N1 and group N2 (neodymium:yttrium-aluminum-garnet laser irradiation [2 W, 200 ml, 10 Hz, with pulse durations of 180 or 320 microseconds), group HF (9.7% hydrofluoric acid etched), and group C (control with no treatment). Dual-cure resin cement was adhered onto the fiber posts after they were covered with a silane agent, and then the posts were placed into the canal space using a Lentulo spiral. The PBS test was performed after all specimens were transversally sectioned (root slices of 1-mm thickness). Data were analyzed with 1-way analysis of variance/Tukey post hoc test (alpha = 0.05). Results: The highest PBS value was observed in group S (middle part), and the lowest value was observed in group C (apical part). There were no statistical differences among the groups regardless of the part. Furthermore, when the PBS values of the different parts of dentin were compared within treated groups, significant differences were observed in all groups except group N2 (P < .05). Conclusions: Within the limitations of this study, it can be concluded that the LAI technique when used with 17% EDTA had a significant effect on the amount of smear layer removed from the root canal dentin, which was also detected in the fracture pattern (adhesive failure [resin-post interface]). However, the various treatments of the fiber post did not improve the PBS of the root dentin.