Effectiveness of Four Different Light-activated Composites Cure with Different Light Energy Densities

Abstract

Background: This study investigated the influence of light energy density (intensity
x time) on the effectiveness of composite cure in view of the curing profiles of lightpolymerization
units with different light- activated composites to determine the
energy density that satisfies adequate polymerization of all light-activated
composites types used in this study.
Materials and methods: This study investigated the hardness of the top/bottom
surfaces and hardness ratio of 2-mm thick composite specimens after exposure to
different light energy densities. Parameters included five light intensities (200, 300,
400, 500 and 600 mW/cm2) and seven curing times (20, 40, 60, 90, 120, 150 and
180 seconds) for each of the four different light-activated composite materials
(Tetric Ceram, Heliomolar, Herculite XRV and Degufill Mineral).
Results: Statistical analysis of the data by using the one-way analysis of variance
revealed that, most of the hardness ratios exhibited a very highly significant
difference according to intensity, composite type and curing time. The results
indicated that, Heliomolar and Degufill Mineral light-activated composites required
approximately (36 J/cm²) energy density for adequate polymerization for a 2-mm
thick specimen while, Herculite XRV and Tertric Ceram light-activated composites
required approximately (12 J/cm²) energy density for adequate polymerization for a
2-mm thick specimen.
Conclusion: This study indicated that, final curing should not be done with energy
density less than (300 mW/cm2 for 120 seconds, 400 mW/cm2 for 90 seconds and
600 mW/cm2 for 60 seconds) for Heliomolar and Degufill Mineral light-activated
composites.