Impact of Preceded Tumor Therapeutic Irradiation on the Microtensile Bond Strength of Universal Adhesives Applied in Self-Etch Mode to Human Dentin In Vitro

The aim of this study was to investigate the effect of preceded tumor therapeutic irradiation on the tensile bond strength of three modern universal adhesives applied in self-etch mode on dentin. Specimens prepared from 135 extracted human third molars were divided into three superior groups. These received either no radiation, 5 Gy, or a total dose of 60 Gy in vitro irradiation, fractionally applied. The samples of each group were further randomly assigned to six subgroups to test three adhesives (Futurabond® U, Voco; AdheSE® Universal Ivoclar Vivadent; Xeno® Select, Dentsply Sirona) in the self-etch application mode (n = 15). Tensile bond strength was determined using a universal testing machine (1.0 mm/min). Data were analyzed with ANOVA (p < 0.01) and Tukey’s test (p < 0.05). The influence of irradiation on the microtensile bond strength of the used dentin adhesives proved to be significant. For each material, a decrease in adhesion value was registered after irradiation. However, only for the material Xeno® Select were significantly reduced adhesion values determined after irradiation with 60 Gy compared to 0 Gy. Within the limitations of an in vitro study, some effects of tumor therapeutic irradiation of human dentin on the tensile bond strength of universal adhesives used in self-etch mode could be observed. Those decreases were only partly significant, depending on the material and the radiation dose. Whether the tensile bond strength on irradiated dentin depends on the particular application mode (etch-and-rinse vs. self-etch) of the universal adhesives remains to be investigated.