Light Emitting Diode in Comparison to Halogen Curing Technology: Microshear Bond Strength of Dental Composite Resin Restorative Material

The aim of this study was to compare the micro-shear bond strength of composite resin cured with halogen visible light and blue light emitting diode curing units. Flat enamel surfaces of 50 segments of teeth were prepared. 50 cylindrical composite resin specimens were bonded to the prepared teeth segments. Specimens were divided into 5 groups, three groups were cured for 10, 20 and 40 seconds using blue light emitting diode and 2 groups were cured for 20 and 40 seconds using halogen light. Specimens were submitted to micro-shear bond test at 1mm / min cross-head speed. Mean micro-shear bond
strengths were analyzed by analysis of variance (One-way ANOVA) and Tukey's test at P<0.05. At 40 seconds curing, the halogen light produced significantly higher bond strength than that of blue light emitting diode. No significant difference was found between both lights at 20 seconds. There were no significant differences in bond strength ratios between 10 and 20 seconds blue light emitting diode, and 20 seconds halogen light. At 40 seconds, the blue light emitting diode produced significantly higher bond strength than that of blue light emitting diode at 10 and 20 seconds, and halogen light at 20 seconds.
It was concluded that despite the higher micro-shear bond strength of halogen light at 40 seconds, blue light emitting diode curing unit provided sufficient output to exceed minimum requirements in terms of composites’ micro-shear bond
strength according to ISO 11405, 1994. During incremental application of composite resin, 10 seconds blue light emitting diode curing time is sufficient to produce acceptable micro-shear bond strength values.