Physicochemical properties of methacrylate resin, calcium hydroxide, calcium silicate, and silicon-based root canal sealers

Introduction
The use of root canal sealer, together with core filing material, is essential to provide hermetic seal in root canal system. However, different types of root canal sealer materials exhibit different properties, which may affect the quality of root canal treatment. Objectives: The aim of the study was to compare pH, solubility, dimensional change, flow, working time, and film thickness of methacrylate resin (EndoRez), calcium hydroxide (Sealapex), calcium silicate (BioRoot RCS), and silicone-based sealer (GuttaFlow Bioseal).

Material and methods
Solubility, dimensional change, flow, working time, and film thickness of root canal sealer materials were assessed based on ISO standard 6876/2012 recommendations. pH of sealer materials was measured using a pH meter. pH, solubility and dimensional change of sealers were evaluated on day 1, 7 and 14.

Results
pH values of Sealapex, BioRoot RCS, and Guttaflow Bioseal ranged between 8.91 and 12.01, whereas EndoRez showed an average pH value of 6. pH of EndoRez increased significantly over time (p < 0.05), while pH of BioRoot RCS decreased significantly (p < 0.05). However, no significant pH change was observed in Sealapex and GuttaFlow Bioseal. BioRoot RCS showed the highest solubility (p < 0.05), and solubility of all sealer materials increased from day 1 to 14, but no significant change (p > 0.05) was noted in BioRoot RCS and GuttaFlow Bioseal, respectively. Dimensional change of BioRoot RCS was significantly higher (p < 0.05), with no significant difference (p > 0.05) between EndoRez and Sealapex at day 1 and day 14. GuttaFlow Bioseal exhibited the highest flow value (p < 0.05). BioRoot RCS demonstrated the longest working time (p < 0.05), while EndoRez showed the lowest film thickness, which was comparable to Sealapex (p > 0.05).

Conclusions
EndoRez is slightly acidic, while the remaining sealer materials are alkalines. All sealers confirmed to ISO standard, except for solubility and film thickness of BioRoot RCS.