Damage characterization of dental nanocomposite adhesive in orthodontic treatment applications

In orthodontic treatments, mechanical characterization of orthodontic bracket bonded to the tooth is essential to determine the bond strength and mechanical behavior of the bracket-adhesive-tooth system. In this study, the linear-nonlinear mechanical behavior and damage characterization of Filtek Z350 XT (3M ESPE) nanocomposite as a dental adhesive material to bond orthodontic brackets to tooth enamel, are investigated using numerical and experimental methods. Full sets of tensile, shear, and mixed modes I/II and I/II/III debonding experiments are conducted to extract the mechanical properties of the nanocomposite adhesive as the bracket/tooth interface. The results of the experiments are used to obtain the cohesive law and the damage model parameters. Three-dimensional finite element models of the bracket debonding tests are developed, while the cohesive zone model (CZM) is used to define the constitutive behavior of the nanocomposite interface under the tensile, shear, and mixed-mode loading conditions. The FE results showed a good correlation with the measured data, indicated the validity of the constitutive model, damage properties, and simulation process. The bond strengths of the nanocomposite adhesive are obtained 8.35 and 4.12MPa in modes I and II loadings, respectively.