A fractional electrical impedance model in detection of occlusal non-cavitated carious.

Identification of occlusal caries remains a major concern for the diagnosis, which is still highly subjective and presents a considerable variability among clinicians. Dentists have been observed an increase of a specifically type of caries lesion, the hidden caries. Among the available techniques to assess the hidden caries, the measurement of electrical impedance has been shown to be one of the most promising. This paper presents a fractional electrical model for the tooth and uses such a model associated to a BioImpedance Spectroscopy (BIS) method based on the current response to a step voltage excitation. An analytical solution for the current response is presented based on a fractional calculus approach. Estimate parameters of the proposed model achieved using an in vitro data acquired in a protocol performed to collect bioimpedance data showed that it seems possible to detect occlusal non-cavitated caries, and that the principal confounding factor in the diagnosis of the incipient occlusal caries, the pigmented areas, can also be differentiated.

An alternative approach in muscle fatigue evaluation from the surface EMG signal.

The aim of this study was to compare the intervals of time between adjacent zero crossings (ZCI), an alternative frequency-temporal parameter, with the root-mean-square (RMS) value and the median frequency (F(med)) from the surface EMG (sEMG) signal in muscle fatigue analysis. Twenty right-handed volunteers performed isometric contractions of right biceps brachii muscle while sEMG signals were collected from it at three different and arbitrary load levels until fatigue. The mean ZCI presented a significant correlation with F(med) but not with RMS value and it also presented lower coefficients of variation than others. The results pointed that mean ZCI properties can contribute more than F(med) and RMS value on the interpretation of the muscle function under fatigue conditions.