Evaluation of adhesive strength in dentin iradiated with ultra short pulse laser (FS) at various energy densities using two adhesive strategies

Abstract

Goal: The study evaluated the adhesive strength of the tooth-restoration interface, promoted by ultrashort pulse laser irradiation, and its influence on the microtensile adhesive strength (µTBS) with different adhesive strategies. Method: Fifty healthy teeth were evaluated, restored with the Single Bond Universal adhesive, using two adhesion strategies: ecth-and-rinse, total acid etching (E) and self-etch, self-etching (SE). To evaluate the adhesive interface, the samples were divided into groups SE (self-etch) and E (etch), and each group was irradiated with pulse fluences of 2 J/cm2, 4 J/cm2, 6 J/cm2 and 8 J/cm2. After irradiation, and restorations were carried out with Z350XT resin, the samples were sectioned with cuts perpendicular to each other, producing toothpicks, which were subjected to microtraction. The Bartlet and Shapiro-Wilks tests were performed and then Two-way ANOVA was applied with 2 additional treatments. When observing differences between factors or interactions, the Dunnett test was applied to compare groups with Controls and Tukey for multiple two-by-two comparisons between the transformed means (α<0.05). The percentages of failure types (µTBS) were calculated in the different groups and the Fisher's Exact test was applied (α<0.05). Result: The results demonstrate that laser irradiation (fs), regardless of the energy density used, did not interfere with the performance of the material at the adhesive interface without prior conditioning, as the values obtained were similar to each other (32-35 MPa). Conclusion: It was concluded that irradiation with different energy densities did not change the adhesive strength of the SE groups, as the groups had similar results between themselves and the Control. However, acid conditioning affected the irradiated groups, as the Control (with acid) presented higher values with a statistical difference in relation to the others.