Influence of Geometrical Configuration of a Translucent Fiberglass Post on the Polymerization of a Dual Cure Resin Cement Analyzed by EPR Spectroscopy

Abstract

This research aimed to study the influence of the geometrical configuration of a translucent fiberglass post on the dual cure resin cement polymerization by electron paramagnetic resonance (EPR) spectroscopy. A 20-mm long, White Post DC no. 1 fiberglass post (FGM, Joinvile, SC, Brazil) was sectioned in half to obtain two different groups of posts: cylindrical and conical. Each post was cemented with AllCem A1 dual cure resin cement (FGM, Joinvile, SC, Brazil) using a root canal model and light cured for 40 s. Following cementation, the post was removed and sectioned to obtain 2 mm samples at different depth of cementation. EPR spectra were obtained 10 min and 24 h after cementation to determine the concentration of free radicals (FR) in the surrounding hardened (cured) dental cement, once the concentration of FR is proportional to the light intensity at the restoration point. No significant decrease was observed in light transmission through the cylindrical post that affected the FR concentration, at depths up to 5.5 mm. In contrast, a decrease was verified for all samples conical geometry. The light conduction was effective up to 5.5 mm of curing depth when a cylindrical post was used. The cylindrical configuration was more efficient at conducting light to the deepest points of the restoration compared with the conical configuration.