Disclosed is a device (41) for electrochemically whitening teeth. The device (41) comprises an applicator and a spacer (55). The applicator is used for applying an oxidising agent to the teeth which have been brought to contact with a metal salt activating solution. The applicator has the shape of a dental tray having a back curved wall (43) and a front curved wall (45). The spacer (55) is connected to the back curved wall (43) of the applicator. There is a first electrode (49) and a second electrode (53). The first electrode (49) is attached to the back curved wall (43) of the applicator. The spacer (55) precludes a contact of the first electrode (49) with the teeth. The second electrode (53) is attached to the front curved wall (45) of the applicator. The second electrode (53) extends from the front curved wall (45) to directly contact with the teeth when the applicator is worn. The first electrode (49) and the second electrode (53) are configured to transmit electric current though the applicator. The device (41) further comprises a sealing lip (57) for limiting the exposure of non-tooth intra-oral tissues to the oxidizing agent. The oxidising agent undergoes activation and reduction upon transmission of the electric current through it, thereby affecting the whitening of the teeth.
