Disclosed is a photodynamic therapy device (30) for delivery of a photoactivatable composition to a treatment site, such as the surface of a tooth. The device comprises an illuminating member (32) comprising and illuminating element (34) and a power source electrically connected thereto, and an applicator cartridge (10). The applicator cartridge comprises a reservoir (14) adapted to receive a composition comprising at least one component of the photoactivatable composition therein, and an applicator head (12). The applicator cartridge is detachable connected to the illuminating member. The applicator head comprises one or more pores for passing the composition from the reservoir through the applicator head. The composition may then be pushed through the one or more pores when a pressure is applied to the applicator cartridge.
