There are a few different ways to classify stains on your teeth and their candidacy for being removed.
You most likely have extrinsic, intrinsic, and age-related stains. Extrinsic stains are located in the center of your enamel, intrinsic lay in the dentin (the layer beneath enamel), and age-related stains also sit in your dentin, but those are practically impossible to remove. Everyone has some mixture of each stain type. Even if you can’t see it, there’s likely a little bit of each going on.
Electric toothbrushes can help to remove extrinsic stains. We talk about protecting your enamel in this guide by not brushing too hard or applying too much pressure to your gum line. After twice-daily brushing for a couple of weeks (average challenge criteria and length), those extrinsic stains are gently lifted without causing damage to your enamel. Other than that, brushing won’t remove other stains, but it’s still enough to give you a noticeably whiter smile.