Bond strength evaluation of universal adhesives applied in etch-and-rinse mode on sound and irradiated dentin

To evaluate the laboratory microtensile bond strength (µTBS) of universal adhesives applied in etch-and-rinse mode on irradiated and sound human dentin.

Dentin specimens of 135 freshly extracted human third molars were divided in three superordinate groups. Each tooth received either no irradiation (control group), 5 Gy (2 Gy/2 Gy/1 Gy in 3 consecutive days) or the high-level therapeutic dose of 60 Gy (test groups) applied fractionally (2 Gy/day, 5 days/week, 6 weeks). Samples from each group were randomly divided into three subgroups assigned to three established universal adhesives (Futurabond U, AdheSE Universal, Xeno Select) in just the etch-and-rinse application mode (n= 15). Bond strength was assessed with a universal testing machine 15 minutes after application and light curing of the adhesive materials. Statistical analysis was performed using a two-way ANOVA (P< 0.01) and Tukey's test (P< 0.05).

Regarding all experimental groups ANOVA showed significant effects on µTBS of dentin irradiation and the used adhesives (P< 0.01, ANOVA). In nearly all groups, a decrease of µTBS was observed when used on highly irradiated dentin. However, comparing the different groups, no significant influence of high-level radiation on the microtensile bond strength of the three universal adhesives assessed in etch-and-rinse application mode could be determined (P> 0.05, Tukey's test).

Within the limitations of this laboratory study, no significant effects of low- and high-level tumor irradiation on the bond strength of universal adhesives can be detected after application in etch-and-rinse mode. Consequently, this mode of application may be considered a viable option for patients who have undergone radiation therapy when using universal adhesive systems for luting restorative materials.