Effect of preheating of low shrinking resin composite on intrapulpal temperature and microtensile bond strength to dentin

The effect of preheating of the silorane-based resin composite on intrapulpal temperature (ipt) and dentin microtensile bond strength (μtbs) was evaluated. for the ipt,teeth (n=15) were sectioned to obtain discs of 0.5mm thickness (2 discs/tooth). the discs were divided into three groups (n=10/group) according to the temperature of the filtek ls™ silorane-based resin composite during its placement,either at room temperature (23±1°c) or preheated to 54°c or 68°c using a commercial calset™ device. discs were subjected to a simulated intrapulpal pressure (ipp) and placed inside a specially constructed incubator adjusted at 37°c. ipt was measured before,during and after placement and curing of the resin composite using k-type thermocouple. for μtbs testing,flat occlusal middentin surfaces (n=24) were obtained. p90 system adhesive was applied according to manufacturer's instructions then filtek ls was placed at the tested temperatures (n=6). restorative procedures were done while the specimens were connected to ipp simulation. ipp was maintained and the specimens were immersed in artificial saliva at 37°c for 24h before testing. each specimen was sectioned into sticks (0.9±0.01mm2). the sticks (24/group) were subjected to μtbs test and their modes of failure were determined using scanning electron microscope (sem). for both preheated groups,ipt increased equally by 1.5-2°c upon application of the composite. after light curing,ipt increased by 4-5°c in all tested groups. nevertheless,the ipt of the preheated groups required a longer time to return to the baseline temperature. one-way anova revealed no significant difference between the μtbs values of all groups. sem revealed predominately mixed mode of failure. preheating of silorane-based resin composite increased the ipt but not to the critical level and had no effect on dentin μtbs. © 2014.