A plaque detection system is presented including a dental implement and a multi-mode optical waveguide for receiving fluorescence light from a plurality of angles, the fluorescence light traveling along a core of the multimode optical waveguide at different path lengths resulting in modal dispersion. The plaque detection system also includes a detector configured to receive the fluorescence light for detecting plaque, calculus, and/or caries, and communicating plaque identification information of teeth based on frequency domain lifetime measurements. The modal dispersion is used to detect at least one plaque, calculus, and or caries fluorescence area on the teeth. The plaque fluorescence area detected with modal dispersion includes different levels of plaque with respect to a center point of the plaque fluorescence area. Thus, a plaque detection signal depends on a radial distance from the center point of the plaque fluorescence area.