Objective: This study was conducted to evaluate the light irradiance travelling through bulk-fill resin composites of different filler volumes and incremental thicknesses cured at different light curing distances.
Materials and Methods: Forty specimens (n=5) were prepared according to the three levels of the study; filler volume of the bulk-fill resin composite; Filtek™ Bulk Fill Flowable Restorative (BF) and Filtek™ Bulk Fill Posterior Restorative (BP) (3M ESPE, St. Paul, MN, USA), increment thickness (2- or 4-mm thick increment) and light curing distance (zero mm or at 10 mm). Light intensity transmitted to the bottom of the specimen was monitored using a radiometer (P-9710, Gigahertz Optik GmbH, Germany) for 30 seconds from the start of light curing. Additionally, the light attenuation coefficient of bulk-fill materials was calculated. Specimens of 20mm diameter and 1 mm thickness were prepared to measure the contrast ratio for both bulk fill resin composite materials(n=5). Data was statistically analyzed at (α = .05).
Results: Three- way ANOVA showed statistically significant difference of the three levels of the study for both transmitted light irradiance and light attenuation coefficient(p<0.0001). The highest light intensity transmitted was for BR-2mm at Zero Distance (116.20±3.18) while least light transmitted with in BF-4mm. The mean contrast ratio calculated for BF was 0.95± 0.01 and for BR 0.97± 0.01(p=0.0170).
Conclusions: Filler volume contributes to light attenuation of bulk-fill composites. Increment thickness and light curing distance should be accounted for to ensure proper curing of resin composite at its deepest portion.