A dental implement (4) is presented that includes, in one embodiment, a light source (331) configured to emit an excitation light, and at least one optical unit for removing reflected excitation light and receiving a fluorescence light beam from the teeth. The dental implement further includes a detector (333) configured to receive the fluorescence light beam for detecting plaque and communicating a plaque identification signal of the teeth based on frequency domain lifetime measurements via a plaque detection circuit configured to reduce noise generated by a drive train at a drive train frequency (fdt). The plaque identification signal is demodulated to an intermediate frequency (fIF) such that the drive train frequency and the intermediate frequency are derived from a same master clock.
