The resonator assembly for a power toothbrush includes an elongated solid rod made from stainless steel, having a back assembly which includes permanent magnets which interact with an electromagnet in a drive system in the handle of the toothbrush to produce a transverse motion of the rod. A mount member is connected to the rod at a selected point along its length, and is mounted to a toothbrush housing so that the rod resonates about the mount member at a selected frequency.