Shear bond strength of orthodontic brackets after application of resin infiltration, fluoride varnish and casein phosphopeptide-amorphous calcium phosphate fluoride remineralising agents

The aim of this in vitro study is to examine the effects of fluoride varnish, CPP-ACPF and resin infiltration applications used in the treatment of white spot lesion on enamel orthodontic bracket bond strength in the laboratory environment and the amount of residual adhesive remaining on the tooth surface after fracture. We have used upper and lower first and second premolars that were extracted due to orthodontic treatment were used in the study. Inclusion criteria; Teeth that have not received orthodontic treatment before, that are not decayed, have no fractures or cracks, and have not been filled, were selected. While a total of one hundred teeth are divided into five groups, there are twenty teeth in each group. Groups: G1 control group, G2 demineralized and no therapeutic agent applied, G3 post demineralisation CPP-ACPF applied, G4 post demineralisation fluoride varnish applied and G5 demineralisation resin infiltration applied. While the demineralization-remineralization cycle lasted 21 days, the teeth were kept in demineralization solution for 6 hours and in remineralization solution for 18 hours. During the transition between solutions, the teeth were washed one by one with distilled water. While the applied agents were applied in line with the manufacturer's instructions, the teeth in the third group were stored at 37°C for 24 hours after applying CPP-ACPF for 5 minutes every day. This cycle continued for 1 week. After the brackets were placed, the adhesives were kept in artificial saliva solution at 37°C for 24 hours in order to complete the polymerization. After this process, the teeth were subjected to thermal cycling. Bond strength was tested in the teeth shear device after thermal cycling. The residual adhesive remaining on the tooth surface after the brackets were removed from the tooth was evaluated. The samples were tested for shear bond stregth (SBS) using a universal testing machine, and the adhesive remnant index (ARI) was evaluated. One-was ANOVA and post-hoc Tukey tests were used to compare the SBS of the groups. ARI scores were evaluated with the Kruskal Wallis test. The statistical significance was set at P < 0.05. When the bracket attachment values were examined in the study, the difference between Group 1 and Group 4 was statistically significant (p=0.037), the difference between Group 2 and Group 4 was statistically significant (p<0.001), the difference between Group 3 and Group 4 was statistically significant (p= 0.018), the difference between Group 4 and Group 5 was statistically significant (p<0.001). When the ARI results and percentages were analyzed, the difference between Group 1 and Group 4 was statistically significant (p=0.038), the difference between Group 3 and Group 4 was statistically significant (p<0.001), the difference between Group 4 and Group 5 was statistically significant ( p<0.001). According to the results we obtained in our study, the lowest bond strength was obtained in the fluoride varnish applied group, while the lowest AAI score was obtained in the same group. When the intact enamel group was compared with the teeth applied CPP-ACPF and resin infiltration method applied to demineralized enamel, higher bond strengths were obtained in the CPP-ACPF and resin infiltration groups compared to the control group. The group with the highest bond strength was the group in which the bracket was adhered after the resin infiltration was applied. The bond strength obtained in all groups was clinically sufficient.