Bonding potential to intact and ground enamel of all-in-one adhesives

Objectives: The study was aimed at evaluating the bonding potential to intact and ground enamel of new all-in-one adhesives. Methods: The one-component self-etch adhesives AdheSE One (Ivoclar-Vivadent, ASO), Bond Force (Tokuyama, BF), and Xeno V (Dentsply, XV) were tested in comparison with the etch-and-rinse adhesive Prime&Bond NT (Dentsply, PBNT), that was considered as control. Bond strengths to enamel were measured with the microtensile technique. Four extracted molars per group provided the specimens needed for the test. In the teeth meant for testing of adhesion to intact enamel the flattest surface of the crown was chosen and polished with pumice. In the teeth meant for testing on ground enamel a flat surface was created on the buccal or lingual surface of the crown by grinding with wet 600-grit SiC paper. The bonding procedure was performed on the enamel substrate following manufacturers instructions. The bond strengths in MPa, including pre-test failures as ‘zero' values, were statistically analyzed (Kolmogorov-Smirnov test, Levene test, Kruskall-Wallis Non Parametric Analysis of Variance, Dunn's Multiple Range test; p<0.05). Two extracted molars per group were used for scanning electron microscope observations of the ultrastructural characteristics of the enamel-adhesive interface. Results: The following bond strengths were recorded in MPa (mean±standard deviation): intact enamel: ASO 22.3±21.5; BF 27.8±17.3; XV 22.9±21.5; PBNT 36.1±20.5; ground enamel: ASO 25.9±25.9; BF 29.9±21.2; XV 18.7±17.3; PBNT 43.64±26.6. Conclusion: The statistical analysis demonstrated that on both intact and ground enamel the bond strengths achieved by BF were similar to those of the control adhesive, whereas for ASO and XV bond strengths were significantly lower than for PBNT. With regard to microscopic characteristics of the adhesive interface, the all-in-one adhesives had a superficial interaction with enamel and no distinct hybrid layer was seen. Conversely, a thin hybrid layer was formed in enamel by the etch-and-rinse adhesive PBNT.