FIELD : medicine.SUBSTANCE : invention relates to medical equipment and is intended for cleaning teeth. In the method, an electric toothbrush contains an elongated housing and a unitary subassembly inserted into the opening at the proximal end of the elongated housing. Said elongated housing is made open at the proximal end, having at least one groove in the proximal portion of each side of the interior of the housing wall. Said unitary subassembly contains a drive mechanism powered by a battery, a drive shaft, a control circuit electrically connected to the battery, a battery frame for limiting the movement of the battery, a housing interlock and an end cap. Said drive shaft has a distal end configured to accommodate the cleaning head of the toothbrush, and a proximal end connected to the drive mechanism inside the housing. Said housing interlock is configured to hold together the components of the unitary subassembly, with the housing interlock having housing interlock tabs. Said end cap has tabs of the end cap, with the housing interlock and end cap being permanently coupled together by a slot in each tab of the end cap and a protrusion on each corresponding housing interlock tab located on the housing interlock. Said housing interlock tabs and the tabs of the end cap are located in elastic contact with the said at least one groove in the elongated housing for fixing the unitary subassembly in the housing.EFFECT : invention allows for easy assembly, greater strength and control of vibrations transmitted to the user through the handle of the toothbrush.8 cl, 8 dwg