An oral care appliance (100), such as an electric toothbrush, utilizing non-linear resonant systems is described herein. In one exemplary embodiment, the oral care appliance includes a longitudinal shaft (102), a brush head (130), and a handle (190). The handle includes a motor (140) that generates a first amplitude (404) for the brush head based on the brush head being outside of the user's mouth, when no mass is applied to the brush head. In response to the brush head being inside of the user's mouth, when mass is applied, such as by pressing the brush head against the teeth, the motor causes a second amplitude (410) to be generated for the brush head that is larger than the first amplitude.
