Evaluation of the effects induced by radiotherapy on dentin during endodontic instrumentation using a novel...

This study evaluated a novel methodology for assessing dentin wear resistance and morphological changes in teeth submitted to conventional (CR) or hypofractionated radiotherapy (HR).

Fifteen maxillary canines were divided into three groups: control, CR (60 Gy, 2 Gy/day) and HR (55 Gy, 2.75 Gy/day). The roots were sectioned 3 mm from the apex and 3 mm above and fixed in acrylic resin and tested on a universal testing machine by measuring the force required to wear away the dentin. The specimens were submitted to microhardness analysis with indentations at 50, 100 and 150 µm from the radicular canal surface, scanning electron microscopy (SEM) to identify cracks and energy dispersive X-ray spectroscopy (EDS-X) to quantify calcium (Ca) and phosphorus (P) and analyze the Ca/P ratio.

No significant difference in wear resistance (MPa) was detected between the irradiated groups (CR: 0.102 ± 0.01, HR: 0.111 ± 0.01) and the control group (0.114 ± 0.02) (p > 0.05). Lower microhardness values were observed in the irradiated groups (CR: 37.92 ± 5.78, HR: 32.71 ± 4.37) compared to the control (50.00 ± 3.31), with no difference between them (p > 0.05). The irradiated groups had a higher number of cracks compared to the control, and there was no statistically significant difference in the Ca/P ratio values between the groups tested (p > 0.05).

The new method assessed the wear resistance of dentin after radiotherapy reliably. Although wear resistance and the Ca/P ratio were not altered, both radiotherapy protocols reduced dentin microhardness.