Smart brackets for 3D-force-moment measurements in orthodontic research and therapy - developmental status and prospects.

BACKGROUND AND AIM: Quantitative knowledge of the three-dimensional (3D) force-moment systems applied for therapeutic tooth movement is of utmost importance, with regard to the predictability of the course of tooth movement, as well as the reduction of traumatic side effects. The concept of a smart bracket with an integrated sensor system for 3D force and moment measurement has recently been published. The feasibility of this approach has been demonstrated using finite-element (FE) simulations and a 2.5 times enlarged real smart bracket model. The aim of this study was to develop and to mechanically characterize the first wire-mediated, true-scale smart bracket.

MATERIALS AND

METHODS

A true-scale smart bracket was built using a stress-sensor chip (having a surface area of 2 x 2.5 mm(2)) and a conventional bracket slot. This bracket was calibrated on a biomechanical system for 3D application and measurement of forces and moments, then its measurement accuracy was evaluated.

RESULTS

With the exception of the bucco-lingually-oriented force component, the embedded sensor system was capable of reconstructing the applied force-moment components with sufficient accuracy. The standard deviations for the differences between applied and inferred values were 0.07 N, 0.07 N and 0.26 N for the components F(x), F(y) and F(z), and 0.76 Nmm, 1.09 Nmm and 0.22 Nmm for the components Mx, My and Mz.

CONCLUSIONS

We were able to construct true-scale, wire-mediated smart brackets. Work on improving the sensor system's buccolingual sensitivity is still in progress. Improved smart brackets with wire-mediated energy transmission could be applied in the near future in orthodontic training as an objective feedback tool, as well as in biomechanical research. Broad clinical application of smart brackets requires integration of telemetric components for data and energy transmission. Such components are now being developed. Future clinical application of smart brackets may contribute in reducing the negative side effects of fixed appliance therapy such as root resorption, while enhancing therapeutic efficiency.