I found this post because I too struggle with brushing my teeth, though not for sensory processing reasons. I didn’t have an account on the site yet, but I made one to respond to this because you deserve much better answers than the ones you’ve gotten here. Clearly you haven’t been understood. I’ve been thinking on this and had a difficult time thinking of things you can do while in the process of brushing your teeth that are fun and distracting in a game-like way, like Pokemon go, but I’ve been trying to think of other motivators that could make you feel more happy while brushing. One that I thought of is a sticker chart! Hear me out, I know you’re a Grandmother and stickers are generally considered something for kids, but you can find lovely well-illustrated stickers from artists on etsy. Having a chart in sight with art you enjoy that grows every day that you brush your teeth could help you feel more happy and proud of yourself, and maybe even distract you in the moment if you find stickers you’re excited to see make it to the chart. I’ll be continuing to think on this, and if this answer is unhelpful please let me know and why, because I’d like to help brainstorm some more ideas.