Application of ESR Spectroscopy in the Study of the Light Efficiency of a Dental Translucent Fiberglass Post to Promote Polymerization

ESR spectroscopy allows for detection and quantification of free radicals (FRs) in a sample, which can be associated with the degree of monomer-to-polymer conversion (DC) of dental composites. This research seeks to probe the capacity of a translucent fiberglass post (TFP) to transmit light through its axis and promote polymerization by analyzing the amount of FRs in the sample as a function of the increasing length of a cylindrical TFP. A photopolymerizable dental composite resin was used to ensure that all FRs detected by ESR spectroscopy were generated by light-cure. The results revealed that the introduction of a 4-mm post decreased the DC by approximately 50% compared with irradiation in the absence of the post. In addition, increasing the length of the post dramatically reduced the amount of free radicals detected. This suggests that the TFP may have absorbed a large portion of the radiation, and the DC of resinous materials in the apical part of the root canal may be not sufficient to guarantee the fixation of the post.