There is currently no scientific evidence to suggest that using an electric toothbrush will cause lip fillers to fade faster. Lip fillers are injected into the lip tissue, not the surface, so regular activities such as brushing your teeth, whether manually or electrically, shouldn't affect the longevity of your fillers. However, excessive and repetitive movement of the lips, such as frequently pursing or puckering your lips, may potentially cause the filler to metabolize slightly faster. This varies from person to person and is also dependent on the type of filler used. Remember, it's important to follow aftercare instructions provided by your healthcare provider post-injection, and maintain regular communication about any concerns or queries you might have.