Effect of heat application on the physical properties and chemical structure of calcium silicate-based sealers

To determine the effect of heat application on the setting and chemical properties of HiFlow BC Sealer and compare to other calcium silicate (CSBS) and epoxy resin-based root canal sealers.

AH Plus, BioRoot RCS (BioRoot), Endosequence BC (Endosequence), and HiFlow BC (HiFlow) sealers were placed at 37 °C or subjected to heat at 200 °C for 10 or 30 s, followed by incubation at 37 °C in a humidified incubator during experiments. Setting time, viscosity, and flow were assessed, and changes in chemical structure were evaluated using the Fourier-transform infrared spectroscopy (FTIR). Thermogravimetric analysis was also used to evaluate the weight change (%) of the sealers upon heating from room temperature to 37 °C or 200 °C at a rate of 20 °C/min. Data were analyzed using a two-way ANOVA with a Bonferroni post-hoc test (p = 0.05).

Application of heat extended the setting time for Endosequence and HiFlow but resulted in a faster setting of AH Plus and BioRoot. The highest flow and lower viscosity were observed in HiFlow at high temperature (p < 0.05), whereas the lowest flow with the highest viscosity and greatest weight loss were observed in BioRoot after heat application (p < 0.05). FTIR spectra demonstrated no changes to functional groups after heat application, except for the strong H-O-H absorption peak corresponding to water in BioRoot.

Endosequence and HiFlow showed similar chemical properties with a higher flow and lower viscosity in HiFlow after heat application. Heat application resulted in reduced flow, increased viscosity, and weight loss for BioRoot. The setting of AH Plus was fastened with heat, while its weight loss, viscosity, and flow characteristics were stable.

HiFlow, Endosequence, and AH Plus can be all used with WVC obturation techniques. Heat application resulted in minor changes in their physical properties including setting time, flow, weight loss, and chemical properties, while BioRoot showed a significant amount of weight loss, increase in viscosity, and reduced flowability after heat application.