Related Experiment Video
Updated: Jun 8, 2026
Evaluating the Effects of Different Polishing Methods on Color Stability of Dental Restorations in Pediatric Dentistry
Published on: June 6, 2025
The effect of irradiation distance on microhardness of resin composites cured with different light curing units
Isil Cekic-Nagas1, Ferhan Egilmez, Gulfem Ergun
1Research associate, Dental School of Technology, Hacettepe University, Ankara, Turkey.
Objectives:
The aim of this study was to compare the microhardness of five different resin composites at different irradiation distances (2 mm and 9 mm) by using three light curing units (quartz tungsten halogen, light emitting diodes and plasma arc).
Methods:
A total of 210 disc-shaped samples (2 mm height and 6 mm diameter) were prepared from different resin composites (Simile, Aelite Aesthetic Enamel, Clearfil AP-X, Grandio caps and Filtek Z250). Photoactivation was performed by using quartz tungsten halogen, light emitting diode and plasma arc curing units at two irradiation distances (2 mm and 9 mm). Then the samples (n=7/per group) were stored dry in dark at 37°C for 24 h. The Vickers hardness test was performed on the resin composite layer with a microhardness tester (Shimadzu HMV). Data were statistically analyzed using nonparametric Kruskal Wallis and Mann-Whitney U tests.
Results:
Statistical analysis revealed that the resin composite groups, the type of the light curing units and the irradiation distances have significant effects on the microhardness values (P<.05).
Conclusions:
Light curing unit and irradiation distance are important factors to be considered for obtaining adequate microhardness of different resin composite groups.
