Evaluation of Bond Strength of Metal and Ceramic Brackets on ResinNanoceramic CAD/CAM Material With Different Surface Treatments

Evaluation of Bond Strength of Metal and Ceramic Brackets on Resin Nanoceramic Cad/Cam Material With Different Surface Treatments Aim: With increasing number of adults seeking orthodontic treatments, orthodontists continue to debate the optimal method for bonding brackets to ceramic surfaces. This study evaluated the effects of different surface conditoning methods including Ti:sapphire femtosecond (Fs) and Nd:Yag lasers, silica coating with Cojet, etching with hydrofluoric acid (HFA) and orthophosphoric acid (OPA) on the shear bond strength (SBS) of metal and ceramic brackets bonded to resin nanoceramic (Cerasamart, GC Europe) material. Materials and Methods: In total, 170 ceramic specimens were prepared and divided into two groups, according to brackets used. In each group, the following five subgroups were prepared; OPA, HFA, Cojet, Nd:Yag laser, Ti:sapphire laser. Maxillary central brackets were bonded using a light-cured adhesive. The samples were stored in distilled water at least 24 hours at room temparature and then thermocycled 1000 times. Extra samples were prepared and examined using scanning electron microscopy (SEM) and 3D profilometer. SBS testing was performed, failure and fracture modes were classified. Two way ANOVA, Tukey's HSD tests were used to compare SBS among the five subgroups. Chi-Square test was used to determine differences between ordinal failure and fracture modes data. Wilcoxon signed rank test was used to determine surface roughness differences(P<0.05). Results: All conditioning methods caused acceptable SBS, metal brackets had higher SBS than porcelain brackets, but this difference reached statistical significance only in Fs laser group (13.013±2.425&9.68±1.946, p<0.05). All surface conditioning methods caused significantly higher surface roughness compared to non-conditoned specimen (p<0.05). Both acid treatment, caused surface modification due to polymer content of resin nanoceramic. Homogeneous and regular surfaces were observed in the ablation pattern with the Fs. Conclusion: Within the limitations of this in vitro study, Fs laser can be an alternative method for surface conditioning in orthodontics after overcoming high cost. In addition to HFA, OPA can be used as a chemical conditioning agent in resin nanoceramic materials.