Curing potential of experimental resin composites filled with bioactive glass: A comparison between Bis-EMA and UDMA based resin systems

Abstract

OBJECTIVES
To evaluate the degree of conversion, light transmittance, and depth of cure of two experimental light-curable bioactive glass (BG)-containing composite series based on different resin systems.
METHODS
Experimental composite series based on either Bis-EMA or UDMA resin were prepared. Each series contained 0, 5, 10, 20, and 40wt% of BG 45S5. Reinforcing fillers were added up to a total filler load of 70wt%. The degree of conversion was evaluated using Raman spectroscopy, while light transmittance was measured using visible light spectroscopy. The depth of cure was estimated from the degree of conversion data and using the ISO 4049 scraping test.
RESULTS
Replacement of reinforcing fillers with BG can diminish the degree of conversion, light transmittance, and depth of cure. The effect of BG on the aforementioned properties was highly variable between the experimental series. While in the Bis-EMA series, the degree of conversion was significantly impaired by BG, all of the composites in the UDMA series attained clinically acceptable degree of conversion values. The reduction of the degree of conversion in the Bis-EMA series occurred independently of the changes in light transmittance. The UDMA series showed better light transmittance and consequently higher depth of cure than the Bis-EMA series. The depth of cure for all composites in the UDMA series was above 2mm.
SIGNIFICANCE
While the Bis-EMA series demonstrated clinically acceptable curing potential only for 0-10wt% of BG loading, an excellent curing potential in the UDMA series was observed for a wide range (0-40wt%) of BG loadings.