Simple SummaryThe alterations on dental implants seen after therapeutic radioiodine-131 exposure have important clinical impact. Several microstructural alterations start to appear at 24 h up to 2 weeks after exposure; this affects the pores walls which tend to be eroded.AbstractBackground: The aim was to assess, in vitro, the effects of radioiodine-131 (I-131) on the structure of titanium implants. Material and Methods: A total of 28 titanium implants were divided into 7 groups (n= 4) and irradiated at 0, 6, 12, 24, 48, 192 and 384 hours. At the end of the experiment, each sample was investigated via scanning electron microscopy (SEM) and electrochemical measures. Results: The control sample revealed a smooth and compact surface. The small micro-sized porosity is slightly visible at the macroscopic level, but the precise details cannot be observed. A mild exposure to the radioactive solution for 6 to 24 h showed a good preservation of the macro-structural aspects such as thread details and surface quality. Significant changes occurred after 48 h of exposure. It was noticed that the open-circuit potential (OCP) value of the non-irradiated implants move toward more noble potentials during the first 40 min of exposure to the artificial saliva and then stabilizes at a constant value of −143 mV. A displacement of the OCP values toward more negative values was observed for all irradiated implants; these potential shifts are decreasing, as the irradiation period of the tested implants increased. Conclusion: After exposure to I-131, the structure of titanium implants is well preserved up to 12 h. The eroded particles start to appear in the microstructural details after 24 h of exposure and their numbers progressively increase up to 384 h after exposure.