Evaluation of the Impact of Thermal Exposure on Endodontic Sealers

Objectives: To evaluate the microscopic and physicochemical changes of different endodontic sealers after been exposed to high temperatures
Methods: Eight endodontic sealers were used for this investigation (MTA Fillapex®, Guttaflow II®, Guttaflow Bioseal®, TopSeal®, 2Seal®, Roeko Seal®, Adseal®, AH Plus®, and EndoRez®). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were conducted. Scanning electron microscopy (SEM) at 2000X, and 4000X was used to evaluate the topographical changes of the cements exposed to 230°C using a continuous flow obturation device. Each specimen was prepared in cylindrical aluminum capsules and two sites (external surface and inner core) were analyzed from each sample. Sealer composition before/after thermal exposure was analyzed by energy-dispersive X-ray spectroscopy (EDS).
Results: DSCs and TGAs analyses showed some sealers to be thermally vulnerable at 230°C, inducing physical state changes and mass loss up to 30% (MTA Fillapex^®) while others seemed to be more stable and no mass loss was observed (Guttaflow II^® and Guttaflow Bioseal^®). Chemical composition of certain sealers may vary after thermal exposure. All cement surfaces showed some level of physical change when analyzed externally in SEM. Presence of voids (Roeko Seal^® and Adseal^®) were evident; while others seem to present a smoother surface after heat exposure (MTA Fillapex^®).
Conclusions: Thermal endodontic obturation techniques may negatively influence the behavior and physicochemical properties of certain endodontic sealers, suggesting that this technique should be used only with some biomaterials.