Effect of different light intensities on the degree of conversion of Dual-cured resin cement at different depths of translucent fiber posts

Abstract

The aim of this study was to investigate the effect of different light intensities on the degree of conversion (DC) of a dual-cured resin cement at different depths of fiber posts. Methods: For simulating root canal spaces, 30 molds were prepared using a condensational silicon impression material with putty consistency. DT Light-Posts were cemented in simulated post spaces using Duo-Link resin cement. The specimens were light-cured with three different light intensities of 600, 800, and 1100 mW/cm2 for 40 s. The DC of the cement was obtained at three depths (cervical, middle, and apical) using FT-Raman Spectrometer. Data were analysed using ANOVA (2-way & One-way) and Tukey's test ( = 0.05). Results: Speciments cured with 800 and 1100 mW/cm2 presented significantly higher DC than those cured with 600 mW/cm2 [(p = 0.008), (p< 0.001) respectively]. But the differences were not significant between 800 and 1100 mW/cm2 (p = 0.345). For all the groups there were significant decreases in DC values when the depth increased (p< 0.05), leading to lowest values for the apical regions. Cervical and middle regions revealed no significant differences in DC values when using different light intensities [(p = 0. 75), (p = 0.43) respectively]. However, in the apical region the DC values in 800 and 1100 mW/cm2 were higher than those in 600 mW/cm2 [(p = 0. 011), (p< 0.001) respectively]. But in 800 and 1100 mW/cm2 the DC values were not statistically different from each other (p = 0.093). Conclusions: Increasing the light intensity from 600 mW/cm2 to 800 mW/cm2 was effective in gaining higher DC values in the apical regions of the post spaces. But no difference was observed in the DC when increasing the light intensity from 800 mW/cm2 to 1100 mW/cm2.