Curing kinetics of a photo-polymerized dental sealant

To evaluate the effect of using a variety of light-curing sources on the extent (monomer conversion) and rate of cure of a light-cured dental sealant.

Infrared spectroscopy recorded real-time polymerization of a self-cured and a light-cured sealant when the latter was exposed using manufacturer's recommendations [quartz-tungsten-halogen (QTH)] for 20 seconds as well as to other light sources: high intensity QTH, plasma arc light (PAC), and second-generation blue light emitting diode (LED) units. Specimens were heated to 37 degrees C and the degree and rate of conversion were recorded at each second for 300 seconds. Conversion extent and rate were compared among light units as well as to the self-curing product. Five replications for each test condition were performed.

After 300 seconds, self-curing product conversion was equivalent to all light-exposed specimens. The self-cured rate of cure was significantly lower than all light-cured scenarios. The high intensity QTH light provided equivalent conversion as conventional 20-second QTH exposure (control) in only 10 seconds. The PAC light required similar exposure time as conventional QTH treatment. Second-generation blue LED units reached conversion similar to control in only 10 seconds, while one light required only 5 seconds' exposure.