A method and system for monitoring the location of an oral care device (102) within the mouth of a user, includes: an oral care device (102) having a light source (104); an optical sensor (112) configured to receive light emitted by the light source and to receive light reflected from a user using the oral care device; a computing device (110) adapted to receive and process signals generated by the optical sensor, and programmed to: detect at least one facial feature of the user from the received light reflected from a user; estimate the location of the user's teeth according to the detected facial feature; determine a location of the light source according to the received emitted light; compare the location of the light source to the location of the teeth to estimate the position of the oral care device with respect to the teeth of the user.