Effect of different times of solvent evaporation and pH in two self-etching adhesive systems on the shear bond strength of metallic orthodontic brackets

Objectives The aim of this study was to evaluate the shear bond strength (SBS) of metal brackets bonded with two self-etching adhesives using different times of air drying. Materials and methods 120 healthy bovine incisors were divided into 6 groups ( n=20). Transbond Plus Self Etching Primer and Adper Easy One Self-Etch Adhesive were gently dried at a distance of 20 cm for 3 different times (5 s, 10 s and 15 s). Metal incisor orthodontic brackets were used. The pH of the adhesives was tested with indicator strips and the specimens were tested using a universal testing machine (Instron 3342). Once debonded, each specimen was examined to identify the failure mode (ARI) and SEM was utilized to visualize the enamel conditions. SBS data were subjected to Two-way ANOVA and Tukey tests, while ARI data were analyzed using the Kruskal–Wallis test ( p=0.05). Results Statistically significant differences were found between Groups Transbond 5 (11.72±1.52), Transbond 10 (15.25±2.27) and Transbond 15 (20.45±1.93), with increases in SBS values as exposure time to the air jet was increased. For adhesive Easy One, there was no statistically significant difference between Groups Easy One 5 (13.10±3.46) and Easy One 10 (16.43±2.56), or between Groups Easy One 10 and Easy One 15 (18.43±2.46). There were no differences between ARI values in the tested groups. Conclusions The SBS of the self etching adhesive was directly influenced by the length of time air drying was applied. The pH did not affect the shear bond strength and SEM showed conserved enamel after debonding, suggesting that a smaller amount of adhesive on the enamel surface is better.