The effects of light-activation source on restorative materials were evaluated in vitro by Knoop microhardness in two depths.
Method:
Human teeth were sectioned in 30 blocks and cavity preparations of 1.6 mm were performed with diamond burs. Teeth were distributed into 2 groups according to restorative material (n=5): resin-modified glass ionomer material-RMGI (Vitremer-3M ESPE) and composite resin-CR (Z250-3M ESPE). Each group was divided in three subgroups and activated by quartz-tungsten-halogen lamp (QTH; 24 J/cm2), argon-ion laser (AL; 24.9 J/cm2) or Light Emitting Diode (LED; 24 J/cm2). The blocks were longitudinally sectioned and the restorative materials were evaluated by Knoop microhardness, which was carried out by five indentations located on the center of the restorative material, at the top (0mm) and at the base, 1.6 mm from the activation source. Data were evaluated by 2-way ANOVA and Tukey tests (p<0.05) considering the factors light source and depth.
Result:
ANOVA showed statistical significant differences for ‘depth’ for both CR and RMGI. KHN results were statistically higher at 0 mm than 1.6 mm for CR. The results of CR in (KHN) were: 0 mm–71.9a; 1.6 mm–51.8b. KHN results were statistically higher at 1.6 mm than 0 mm for RMGI. The results of RMGI in (KHN) were: 0 mm–43.7b; 1.6 mm–66.7a.
Conclusion:
The CR had higher KHN values on 0 mm than 1.6 mm from the activation source. The RMGI had higher KHN values on 1.6 mm than 0 mm from the activation source. The activation source did not influence the KHN values for both tested materials (grant number FAPESP 2009/02240-3).