Pump toothbrush comprising a refillable cartridge containing dentifrice material, a pump head having an elastic compressible button, and a brush head having a spout opening attached with a slit valve. The slit valve prevents backflow and drying of the dentifrice material at the spout opening. The slit valve opens and closes automatically with the pumping action. The dispensing mechanism and cartridge structure are applicable to manual and electrical pump toothbrushes.