Effect of ionizing radiation on the microstructure and physical properties of endodontic gutta-percha points

Patients undergoing radiotherapy for head or neck cancer often require root canal treatments, which can be compromised by the effects of radiation. This investigation aimed to determine whether ionizing radiation (IR), in doses similar to those used in conventional therapy, affects the surface and physicomechanical properties of various brands of endodontic gutta-percha points (EGPs).

One hundred and twenty-three EGPs from three brands (Meta-Biomed, Dentsply, and Hygenic) were divided into groups and either exposed or not exposed to IR at a total dose of 50 Gy, divided into 25 fractions. Tensile strength and microhardness tests were performed on all EGPs. Scanning electron microscopy was utilized to identify possible microstructural surface changes due to IR exposure. The proportion of organic to inorganic components in each brand was also determined.

Exposure to IR resulted in significant changes only in the EGPs from the Meta-Biomed brand, including a notable decrease in tensile strength and an increase in microhardness. Furthermore, the surface microstructure of these EGPs displayed dark lines and striations over a large area, with some lines deeply embedded in the center and cavities of variable depths and extensions observed, leading to irregular and non-smooth surfaces. This brand had the highest proportion of organic components.

The physicomechanical properties and surface microstructure of Meta-Biomed brand EGPs were significantly affected by IR at doses used in conventional therapy for head or neck cancer, while the other brands were less affected or unaffected.