Abstract
The aim of the present in vitro study was to evaluate the temperature variation inside the pulp chamber during light-activation of the adhesive and resin composite layers with different light sources. Cavities measuring 8x10 mm were prepared on the buccal surface of bovine incisors, leaving a remaining dentin thickness of 1 mm. Specimens were placed in a 37±1 °C water bath to standardize the temperature. The temperature in the pulp chamber was measured every 10 s during 40 s of light activation of the adhesive system (SBMP-3M/ESPE) and in the three consecutive 1-mm-thick layers of resin composite (Z250-3M/ESPE). Three light source devices were evaluated: Elipar 2500 (QTH), LD Max (LED low irradiance) and VALO (LED high irradiance). The results were submitted to one-way ANOVA with repeated measures and Tukey's test, both with p<0.001. The exothermic reaction warming was observed in the Z250 increments, but not in the SBMP. The high irradiance LED showed a higher temperature average (42.7±1.56 °C), followed by the quartz-tungsten-halogen light (40.6±0.67 °C) and the lower irradiance LED (37.8±0.12 °C). Higher temperature increases were observed with the adhesive and the first resin composite increment light-activation, regardless of the employed light source. From the second increment of Z250, the restorative material acted as a dispersive structure of heat, reducing temperature increases. Regardless the light source and restorative step, the temperature increased with the irradiation time. It may be concluded that the light source, irradiation time and resin composite thickness interfered in the temperature variation inside the pulp chamber.
Highlights
Resin composites are one of the aesthetic materials that most evolved in the last century and currently highlighted in dentistry for esthetic restorations
With the development of light sources and increase in irradiances, the warming in the pulp chamber started to be understood. These temperature increases may occur due to the exothermic reaction of the resin composite during polymerization or due to the energy emitted by the light source, which is absorbed by the restorative material during the light-activation [2]
Among the three light sources, the largest temperature increase occurred during the curing of the adhesive system, followed by the first increment of resin composite (p
Summary
Resin composites are one of the aesthetic materials that most evolved in the last century and currently highlighted in dentistry for esthetic restorations One of these developments was the replacement of benzoyl peroxide for camphorquinone (a light sensitive molecule), which allows the chain reaction polymer network formation to be initiated by light. With the development of light sources and increase in irradiances, the warming in the pulp chamber started to be understood. These temperature increases may occur due to the exothermic reaction of the resin composite during polymerization or due to the energy emitted by the light source, which is absorbed by the restorative material during the light-activation [2]. It is important to control the light-activation time with regards to the irradiance of the light source to allow the temperature increase inside the pulp chamber to remain within a safe range [3]
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