Influence of different orthodontic brackets and chemical preparations of ceramic crowns on shear bond strength

Background Bonding to ceramic restorations remains a major challenge to orthodontists, especially due to an increasing number of adults seeking orthodontic treatment. Aims The objective of this research was to investigate the influence of two chemical methods used for surface conditioning of ceramic crowns, on shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to ceramic surfaces. Methods The study was conducted on 48 prepared specimens of metallic and ceramic orthodontic brackets bonded to ceramic crowns, conditioned with two different etching materials: hydrofluoric acid (HFA), or phosphoric acid, and subsequently, silane. SBS was tested using Universal Testing Machine. The samples were analysed using Scanning Electron Microscope, to determine adhesive remnant index (ARI). Statistical data was processed with ANOVA, and ARI was evaluated using x 2 test, with level of significance α=0.05. Results SBS values of the groups etched with HFA and silane, compared to the groups etched with phosphoric acid and silane, are not significantly increased. However, ceramic brackets show significantly higher SBS values than metallic brackets. Conclusion Both types of ceramic surface conditioning procedures have similar features and provide strong enough SBS values to realize the orthodontic treatment. Also, the assumption that only the type of bracket significantly affects the SBS value can be accepted.