An oral treatment device that emits light onto surfaces of a user's teeth. In one aspect, the oral treatment device includes an intraoral mouthpiece comprising: a lamp support surface; and a lamp. When the lamp is mounted to the lamp support surface, a first contact surface of the lamp contacts a first contact surface of a first electrical contact element of the lamp support surface; and (2) a second contact surface of the lamp contacts a second contact surface of a second electrical contact element of the lamp support surface.