Reduced Irradiation Time in Slow-curing of Resin Composite Using an Intensity-changeable Light Source

Possibility to shorten the total irradiation time in slow-curing with an intensity-changeable light source, Curetron 7 (CT-7), was investigated for four hybrid-type resin composites. Irradiation condition with CT-7 was assigned as 10 or 20 seconds at low light intensity (230mW/cm2) and followed by 20 or 10 seconds at high intensity (600mW/cm2) respectively (i. e., a total of 30 seconds). For a reference, irradiation was carried out for 30 seconds using a halogen lamp (900mW/cm2). After irradiation, mechanical properties of the cured composites—in terms of microhardness and flexural strength—were evaluated. Also, cavity adaptation was examined in standardized, cylindrical dentin cavities treated with an adhesive system. Compared to the reference irradiation, slow-curing with CT-7 produced acceptable mechanical properties and better adaptation. These results suggested that total exposure time of slow-curing with CT-7 could be shortened to 30 seconds.