Moisture-insensitive adhesives: reactivity with water and bond strength to wet and saliva-contaminated enamel

The purpose of this study was to investigate the reactivity with water of a moisture‐insensitive orthodontic primer (Transbond MIP), in conjunction with a no‐mix orthodontic adhesive (Unite), and a moisture‐insensitive adhesive (Smartbond), and to assess their bond strength to wet and saliva‐contaminated enamel relative to the conventional application of the no‐mix adhesive. The reactivity of the moisture‐insensitive products with water was investigated by micro‐multiple internal reflectance Fourier transform infrared spectroscopy (micro‐MIR FTIR). Sixty premolars were divided into two groups of 30 teeth each and, on the buccal enamel surfaces, a standardized volume (0.1 ml) of water or fresh whole saliva was applied. Standard edgewise stainless steel brackets were then bonded to enamel surfaces as follows: (a) Unite, (b) Unite with the Transbond MIP, and (c) Smartbond. The brackets were debonded under shear force at a speed of 2 mm/min and the debonded enamel surfaces were subjected to fractographic analysis. The statistical analysis of the bond strength values was performed by two‐way ANOVA with condition (water, saliva) and adhesive type serving as discriminating variables (n = 10, α = 0.05). The results of the fractographic analysis were evaluated by χ2 test (α = 0.05).