تأثیر نور دهی تأخیری بر استحکام باند Push-out پست گلاس فایبر به نواحی مختلف عاج کانال ریشه

Background and Aims: Delay in light irradiance can improve the polymeric structure and mechanical properties of resin cement and uniform stress distribution. The aim of this study was to evaluate the effect of light activation modes (immediate, 5 and 10-minute delay) on the push-out bond strength of cemented fiber posts with two types of resin cements in different of root canal regions. Materials and Methods: In sixty extractedsingle canal and endodontic therapied roots, FRC Postec Plus were cemented with two resin cements, Nexus3 and Panavia F2.0, in three curing methods, immediate, 5, and 10 minute delay. After 24 hours storing in a dark place, they were cut into three sections: coronal, middle and apical. The push-out bond strength test was performed using the universal testing machine. Failure modes were evaluated using stereomicroscope. Data were analyzed by ANOVA and Tukey post hoc test with P<0.05 as the level of significance. Results: In Nexus3, the immediate light curing had significantly higher bond strength (11.18&plusmn;4.32) than delay methods (P=0.001). In Panavia F2.0, the 5-minute delay had significantly the highest bond strength (13.34&plusmn;4.62) (P<0.05). There was no correlation between the different light curing methods and root canal regions. In Nexus3, the coronal region had higher bond strength (11.83&plusmn;3.7) than that of middle (9.12&plusmn;3.1) (P=0.015), and middle than of apical (5.65&plusmn;2.77) (P=0.00), and coronal than that of apical (P=0.002). In Panavia F2.0, there were not significant differences among regions (P>0.05). Conclusion: Delay in light curing of dual-cure resin cement's had different effects on the push-out bond strength. &nbsp;