Great question! Honestly, we don’t have the full answer to this yet. We do have family members who use Shine with their electric brushes. But it really depends on the style/type of electric brush you use.
You see, one of the ingredients in Shine is baking soda, which is a little ‘gritty’ for lack of a better word. My initial concern is whether the abrasivity of baking soda would cause trouble to the brush head over time. My concern is probably unfounded since you probably replace the brush head every so often anyway.
So, our ‘official’ answer is: provided you are using a common electric brush like a Sonicare or Oral-B, it should be fine. If you are using a more obscure electric brush like the Rotodent which has much smaller moving parts in the brush head, I would hesitate to use Shine with it.