RESUMEN
Bulk-fill (BF) dental resin composites are made to be polymerized in increments of up to 5 mm rather than the 2 mm increment recommended for conventional composites. This project aimed to determine microhardness (MH) profiles of BF resin composites at different depths and varying light cure (LC) distances from the light source in an attempt to mimic varying clinical situations. Forty-eight cylindrical specimens (4 mm diameter and 6 mm height) were prepared from 3 BF composites: Tetric N-Ceram Bulk-Fill (TBF), Filtek One Bulk-Fill (FBF), and Sonic-Fill 2 (SF2). Four different distances (0, 2, 4, and 6 mm) from the LC unit were investigated. Vickers MH was measured at the top and bottom of the samples and at every 1 mm, by creating 3 indentations at each depth. The bottom-top microhardness ratio (MHR) and percentage reduction in MHR were also measured. Data was analyzed using mixed-model repeated-measure ANOVA at 0.05 significance level. The main variables effects "material, LC distance, and depth" were significant (p < 0.001). Increasing LC distance and the depth of the tested BF significantly affected Vickers MH and MHR. None of the tested BF materials had sufficient MHR at the depths of 4-6 mm. SF2 showed the least MHR reduction.
RESUMEN
OBJECTIVE: The objective of the study is to investigate the effect of infection control barrier (ICB) and curing time on irradiance of light cure units (LCUs). METHODS: Irradiance (mW/cm2) of the LCUs at a government dental school were recorded with and without ICB at 0 (T0), 10 (T10), and 20 (T20) seconds using a digital radiometer. Data were analyzed using IBM® SPSS® Statistics Version 17 for Windows software for the analysis of variance and Bonferroni methods at 0.05 significance level. RESULTS: Using ICB resulted in a statistically significant effect on the irradiance mean (P < 0.01). A significant difference existed between the four different brands of LCUs at different time intervals, irrespective of the use of ICB. At T0 and T10, the mean output of Acteon mini-light-emitting diode (LED) was significantly higher than that of either the Kerr Demi Ultra or the Kavo Polylux II. At T20, E-Morlit's mean irradiance was significantly higher than that of Kerr Demi Ultra, which in turn was significantly higher than that of the Kavo PolyLux II. The mean irradiance of the LEDs was significantly higher than that of the halogens irrespective of barrier placement and at all-time points. CONCLUSION: The ICB used in this study resulted in a statistically significant reduction in the irradiance output. No significant difference in the irradiance was found at different curing time intervals for the tested units regardless of ICB usage.
