Effect of non-thermal atmospheric plasma, acid etching, and aging on the bond strength of a universal adhesive to dental enamel

This study in vitro evaluated the effect of non-thermal atmospheric plasma on the bond strength (BS) of a universal adhesive to human enamel, with or without acid etching when subjected to aging. Forty proximal enamel surfaces were randomly assigned to 4 groups according to acid etching (37% phosphoric acid) and plasma treatment (applied for 20 seconds by scanning mode). Afterwards, Scothbond Universal Adhesive was applied, and a composite resin block was built up. After 24 hours of storage, the specimens were sectioned into sticks. Half of the sticks in each group were immediately submitted to the µTBS test and the remaining after 12 months of aging. Data were submitted to three-way ANOVA with subdivided plots (p <0.01) followed by Tukey test (<0.05). The three isolated factors showed statistical difference: time (p <0.001), plasma (p = 0.04) and acid etching (p = 0.006). There was significant interaction only for time-acid etching (p = 0.013). The acid conditioning of enamel increased the BS values after immediate traction, effect not observed for plasma. Aging after 12 months significantly reduced the BS of all groups without statistical difference between them. The authors concluded that unlike phosphoric acid, plasma application did not increase enamel BS.