Thermal analysis of bulk filled composite resin polymerization using various light curing modes according to the curing depth and approximation to the cavity wall

Abstract

ObjectiveThe purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. Material and MethodsComposite resin (AeliteFlo, Bisco, Schaumburg, IL, USA) was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea) using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden) for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. ResultsThe peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. ConclusionIn the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity.

Intrapulpal temperature changes during curing of different bulk-fill restorative materials

“…The conversion of the carbon-carbon double bonds during the polymerization of the light curing materials is an exothermic reaction 35,36) . The light energy absorbed during the irradiation from the curing source also causes a temperature increase with an exothermic reaction 34) .…”

“…The higher temperature increase observed in the SDR group seems to be related to its low filler content. Previous studies have reported that the exothermic reaction of the resinbased materials during polymerization is proportional to the amount of filler present in the resins 24,36,40) . Consistent with the reports, the temperature changes in SDR and Filtek Bulk Fill Posterior were higher than Z250 (control group) which was placed incrementally.…”

Polymerization stress evolution of a bulk-fill flowable composite under different compliances

“…This conversion is correlated with the volumetric shrinkage and modulus development in the polymerization process. It has been shown that the degree of conversion of the methacrylate monomer progressively decreases with increasing filler content [19, 21]; an inverse relationship was also found between the filler content and the magnitude of the polymerization exotherm (i.e., less filled flowable composites would show higher DC and exotherm than conventional composites[22–24]). The exotherm would affect not only the pulp vitality during dental treatment, but also the polymerization process[25].…”

Comparison of photopolymerization temperature increases in internal and external positions of composite and tooth cavities in real time: Incremental fillings of microhybrid composite vs. bulk filling of bulk fill composite

“…However, these studies measured the temperature changes only at the bottom surface of the composites [16,17,19], at the pulpal surface of the dentin [20,21,23,24], or at the center of the composites [18,22]. Chang et al [26] performed temperature measurements at multiple spots in a Class-II cavity with infrared thermography. However, they measured the temperatures only on the external surface of the cavity in the Teflon mold.…”