The effect of zinc oxide nanoparticles deposition for friction reduction on orthodontic wires

Background: In the sliding technique, the reduced frictional forces are associated with rapid tooth movements and better control of the anchorage. Recently, wire coating with different nanoparticles has been proposed to decrease frictional forces. This in vitro study was carried out to coat stainless steel (SS) wires with zinc oxide (ZnO) nanoparticles in order to determine the effect of this coating on friction between wires and orthodontic brackets. Materials and Methods: Eighty 0.016 inch and 0.019 inch × 0.025 inch SS wires with and without ZnO nanoparticles were used in 80 orthodontic brackets (0.018 and 0.022 systems). The coated wires were analyzed by SEM and X-Ray diffraction (XRD) observations. Kinetic friction between the wires and orthodontic brackets were calculated using a universal testing machine. Frictional forces were statistically analyzed using three-way ANOVA, one-way ANOVA, Student′s t-test and Tukey multiple comparison tests. Results: Coating with ZnO nanoparticles significantly influenced frictional force values ( P < 0.0001). In 0.019 inch × 0.025 inch wires, the frictional forces were 1.6912 ± 0.18868 and 3.4485 ± 0.32389 N in the coated and uncoated wires respectively, (51% reductions). In the 0.016 inch wires, the friction values were estimated to be 1.5668 ± 0.10703 and 2.56 ± 0.34008 N in the coated and uncoated conditions, respectively, (39% reductions). Conclusion: Due to the positive effects of ZnO nanoparticle coating on decreasing frictional forces, these nanoparticles might offer a novel opportunity to significantly reduce friction during tooth movement

Prediction of Penetration Resistance of a Spherical Penetrometer in Clay Using Multivariate Adaptive Regression Splines Model

This paper presents the technique for solving the penetration resistance factor of a spherical penetrometer in clay under axisymmetric conditions by taking the adhesion factor, the embedded ratio, the normalized unit weight, and the undrained shear strength into account. The finite element limit analysis (FELA) is used to provide the upper bound (UB) or lower bound (LB) solutions, then the multivariate adaptive regression splines (MARS) model is used to train the optimal data between input and output database. The accuracy of MARS equations is confirmed by comparison with the finite element method and the validity of the present solutions was established through comparison to existing results. All numerical results of the penetration resistance factor have significance with three main parameters (i.e., the adhesion factor, the embedded ratio, the normalized unit weight, and the undrained shear strength). The failure mechanisms of spherical penetrometers in clay are also investigated, the contour profiles that occur around the spherical penetrometers also depend on the three parameters. In addition, the proposed technique can be used to estimate the problems that are related or more complicated in soft offshore soils

Prediction of Penetration Resistance of a Spherical Penetrometer in Clay Using Multivariate Adaptive Regression Splines Model

This paper presents the technique for solving the penetration resistance factor of a spherical penetrometer in clay under axisymmetric conditions by taking the adhesion factor, the embedded ratio, the normalized unit weight, and the undrained shear strength into account. The finite element limit analysis (FELA) is used to provide the upper bound (UB) or lower bound (LB) solutions, then the multivariate adaptive regression splines (MARS) model is used to train the optimal data between input and output database. The accuracy of MARS equations is confirmed by comparison with the finite element method and the validity of the present solutions was established through comparison to existing results. All numerical results of the penetration resistance factor have significance with three main parameters (i.e., the adhesion factor, the embedded ratio, the normalized unit weight, and the undrained shear strength). The failure mechanisms of spherical penetrometers in clay are also investigated, the contour profiles that occur around the spherical penetrometers also depend on the three parameters. In addition, the proposed technique can be used to estimate the problems that are related or more complicated in soft offshore soils