A Dental Assisting System for Procedures Performed by Air–Turbine Handpieces

摘要

The present thesis introduces a dental assisting system (DAS) for procedures that are performed by air–turbine dental handpieces. Dental restoration is a process that begins with removing carries and affected tissues to retain the functionality of tooth structures. Air–turbine dental handpieces are high–speed rotary cutting tools that are widely used by dentists during this operation. The next stage in the process is filling the cavity with appropriate restorative materials. “Amalgam” and “composite” are two dental restorative materials that are extensively used by dentists. Most old restorations eventually fail and need to be replaced. One of the difficulties in replacing failing restorations is discerning the boundary of the restorative materials. Dentists may remove healthy tooth structures while replacing tooth–colored composites. Although the visibility issue is less challenging for amalgam materials, replacing them still results in loss of healthy tooth layers. Developing an objective and sensor–based method is a promising approach to monitor restorative operations and prevent removal of healthy tooth structures. The designed DAS uses the audio signals of ATDH during the cutting process. Audio signals are rich sources of information and can be analysed to identify a particular zone of cutting. Support vector machine (SVM), a powerful algorithm for classification, is employed to differentiate the tooth structures from composite/amalgam samples based on their cutting sounds. The averaged short–time Fourier transform coefficients are selected as the features; and the performance of the SVM classifier is evaluated from different aspects such as number of features, feature scaling methods, and the utilized kernels. The obtained results indicated capability and efficiency of the proposed scheme. The developed DAS can also measure the speed of ATDH, and maintain it during loaded conditions. An indirect speed measurement method is introduced based on the vibration/sound of ATDH. This measurement technique is explained theoretically based on the rotating unbalance concept and the vibration of a fixed–free beam. To control the speed, a proportional–integral controller is designed and tested. The feasibility of this controller in maintaining the speed in the loaded conditions was confirmed by simulations and experiments.