Setting Reaction of Dental Resin-Modified Glass Ionomer Restoratives as a Function of Curing Depth and Postirradiation Time

Specular reflectance fourier transform infrared (sr-ftir) spectroscopy was used to study the setting reaction of dental resin-modified glass ionomer (rmgi) restoratives as a function of curing depth and postirradiation time. two light-cure and one tri-cure rmgi materials were selected and used according to the manufacturers' instructions. samples were prepared by filling the mixed materials into custom-made molds and then light-irradiating using a dental curing light. the degree of conversion and the extent of acid-base reaction of the materials at different depths (0,1,2,and 4 mm) and postirradiation times (10 min,1 day,and 7 days) were determined using sr-ftir spectroscopy in conjunction with the kramers-kronig (k-k) transformation. the setting reaction was also investigated using microhardness measurements. the results showed that the depth of cure increased over time by the continuous acid-base reaction rather than photopolymerization or chemical polymerization. microhardness tests seemed less suitable for studying the setting reaction as a function of postirradiation time,probably due to softening from the humidity. analysis using specular reflectance in conjunction with the k-k algorithm was an easy and effective method for monitoring the setting reaction of dental rmgi materials. © 2015 young kyung kim et al.