Abstract
Aims: To study the effect of different curing modes of Light emitting diodes (LED) curing unit on the depth of cure (DOC) of composite resin with light and dark shades and compare the results with conventional curing method by the use of halogen curing light. Materials and Methods: A total of 40 cylindrical composite resin samples (4mm diameter and 6mm height) were prepared, 20 of light shade and 20 of dark shade. They were subjected to four curing modes (n=5 for each group): conventional halogen light, and three modes related to the LED light curing unit (LCU) which were: Fast (F); Ramped (R); and Pulsed (P). The samples were irradiated to the time required by the manufacturer for each curing mode, and a digital micrometer was used to measure the depth of cure according to scraping method described in ISO 4049:2000. Data were collected and analyzed for comparison. Results: No significant difference was found in the DOC of composite irradiated by LED curing light for all of the three curing modes or shade. However, the LED produced significantly greater depths of cure when compared with conventional halogen curing unit for both shades. The lighter shade was cured to a significantly greater depth than dark one when considering halogen LCU. Conclusions: All curing modes of the LED light can produce similar DOC regardless of composite shade when irradiated to the time recommended by the manufacturer. However, Curing with conventional halogen curing unit yielded the least DOC values for light or dark shades when compared with LED units. Longer irradiation times are needed to cure dark shades by the use of halogen LCUs.
