US researchers have created a dental health sensing system that uses off-the-shelf electric toothbrushes for dental condition detection.
The work by the team at Carnegie Mellon College of Engineering in collaboration with the University of Pittsburgh School of Dental Medicine is published in Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies.
The ToMoBrush (Tooth Monitoring Brush/Tomorrow’s Toothbrush) explores the potential of using an off-the-shelf electric toothbrush with minimal hardware modification for dental health sensing to enable regular, at-home dental self-examinations.
Rather than viewing a toothbrush purely as a cleaning instrument, ToMoBrush leverages the fact that an electric toothbrush emits acoustic signals that are generated by rapid automatic bristle vibrations. When the brush is in contact with a tooth, the tooth also vibrates along with the toothbrush and produces distinct acoustic signals depending on the condition of each tooth.
The team further developed a data-driven signal processing pipeline to detect and discriminate different dental conditions, such as cavities, plaque, and food impaction, as well as variations in electric toothbrushes, such as brand, battery charge, and bristle formation. To tackle these variables, the team modelled the vibration system including toothbrush, tooth resonance, as well as brushing strength and movement.
In their paper, the researchers propose an algorithm to separate these different factors and extract clean tooth resonance signatures based on a key observation. Though these factors share the same frequency band, their rates of change across the frequencies are different. By adapting a technique that is widely used in speech processing to separate the glottal excitation and vocal tract resonances, the team proposes converting the signal into the cepstrum domain where these distinct behaviours are easily separable.
The team believes such a system can supplement the dental health care system, even for those with access to professional dental care, by providing early warnings of potential issues in between dental visits.
