A comparative evaluation of curing depth and compressive strength of dental composite cured with halogen light curing unit and blue light emitting diode: an in vitro study.

PURPOSE To evaluate the curing depth and compressive strength of dental composite using halogen light curing unit and light emitting diode light curing unit. MATERIALS AND METHODS Eighty cylindrical composite specimens were prepared using posterior composite P60(3M). Forty specimens, out of which 20 samples (group A) cured with halogen light and 20 samples (group B) cured using light emitting diode (LED) light were checked for curing depth according to ISO 4049. Remaining 40 samples out of which 20 samples (group I) cured using halogen light and 20 samples (group II) cured using LED light were checked for compressive strength using Instron universal testing machine. RESULTS Twenty samples (group A) cured with halogen light showed better curing depth than 20 samples (group B) cured with LED light. Twenty samples (group I) cured with halogen light showed almost similar results as 20 samples (group II) cured with LED light for compressive strength. CONCLUSION Halogen light commonly used to cure composite resin have greater depth of cure, when compared to LED light, while both the lights produced compressive strength which is almost similar. CLINICAL SIGNIFICANCE Lower depth of cure with the LED unit, compared to the QTH unit, is associated with different light scattering due to differences in spectral emission. LED technology differs from QTH by the spectral emission that favorably matches the absorption spectrum of camphorquinone.