Abstract: A toothbrush includes a handle and a function part. The handle includes an installation end in which an insertion hole is defined axially. An opening is defined through the wall of the installation end and communicates with the insertion hole. A guiding groove is formed axially in the inside of the insertion hole. The function part includes a head with bristles, and an insertion which extends from one end of the head and has a through hole defined therethrough. A spring member is secured in the through hole and includes a protrusion. The insertion is inserted into the insertion hole of the handle, and the protrusion is movably engaged with the guiding groove until the protrusion is engaged with the opening when the insertion is positioned in the insertion hole. The spring member is not deformed when the protrusion moves along the guiding groove.

Abstract: A toothbrush capable of seeing dental plaque comprises a main body, a detecting light source, a battery, and a control circuit. The main body includes a head and a handle. The head has a plurality of bristles and is replaceable relative to the handle. The detecting light source is arranged at the handle of the main body and emits a wavelength ranged from 400 nm to 700 nm. The battery and the control circuit are arranged at the handle of the handle of the main body. The control circuit is electrically connected with the battery and the detecting light source.