Abstract
To assess the efficiency of different concentrations of sodium hypochlorite (NaOCl) on the bonding of ceramic brackets to dental enamel using different bonding protocols. Ceramic, a polycrystalline bracket, was bonded to 90 extracted bovine incisors using primer + Transbond XT (P+TXT); Optibond S adhesive + Transbond XT (OS+TXT), and OS + Orthocem (OS+OC). Three concentrations of NaOCl (0%, 2.5%, and 5.25%) were used for each material, resulting in nine experimental groups (n=10). The shear bond strength (SBS) assay was performed on a universal testing machine. The surface morphology of the enamel and tooth/bonding material interface was examined under a scanning electron microscope. Kruskal-Wallis and Dunn's tests were performed to compare the non-parametric data (ARI scores). SBS data were analyzed using a generalized linear model. All analyses were performed using the R program and with a significance level of 5%. No significant differences in SBS between the groups with different concentrations of NaOCl (p>0.05). OS+OC group yielded the lowest bond strength values (3.35 MPa_0%, 4.90 MPa_2.5%, 4.68 MPa_5.25%) compared to the other groups, regardless of NaOCl (p<0.05). No significant difference between the materials regarding the ARI score (p>0.05). OS+TXT-5.25% showed significantly higher scores (14.4 MPa) than OS+TXT-2.5% (9.17 MPa) (p<0.05). The surface morphology analysis revealed a change in the etching pattern for types 1 and 2 when NaOCl was used. The different concentrations of NaOCl previously applied onto the enamel surface did not enhance bond strength. OS+OC should not be recommended for bonding with fixed ceramic orthodontic devices.