Personally I just used it once and ended up removing it, but I can see some people using it to ensure their brushing is efficient.
Anyway, it's completely optional, you can just use the brush ignoring the existence of the app.
Also I doubt it’s AI, just doing something fairly basic with the accelerometer data
I’m not tracking my meals. I did use MyFitnessPal for a bit but I didn’t find it useful.
What if you (for whatever reason, doesn't matter) only ate on the left side of your mouth for dinner? You'd spend plenty of time on the left side, but the app might tell you you've done a bad job on the right. Further, depending on what you ate, it might take longer than whatever their predetermined time is to clean the side that had a disproportionate amount of food on it.
What if you have had a tough time with a couple of "problem teeth" that need a bit more love? Is the app capable of tracking where those "problem teeth" are and ensuring that you're spending extra attention there?
I dunno... to me, it seems like it's a no brainer to me when my teeth are clean - I can feel it. Unless a toothbrush has some detailed sensors in the head, I'm gonna seriously doubt its ability to tell me when my teeth are actually clean.
Then I envy you, because the only thing I feel that's different before and after brushing is a generalized "my mouth is sticky on the inside" feeling. I definitely lose track of how much time I spent cleaning each side relatively, and I'm sure there are areas I rarely reach because I don't know the brush isn't touching them.
I'd love having a toothbrush that would monitor if I reach every spot as a baseline; I can handle my problem teeth or any eating side imbalance on my own, especially that there is no rule saying you need to brush exactly 2 minutes (or 2.5 or whatever) and not a second more - I could do my baseline and spend extra 30 seconds or so in the problem areas.
Right before I sleep I also do 4-7-8 interval breathing in bed that slows down my heart rate and gets me calm and sleepy. I use a simple app called iBreathe for that. This breathing session also lets my Apple Watch give me an accurate reading for my heart rate variability (HRV) that gamifies this for me.
(I imagine a system like this would need at least two accelerometers - one close to the tip, and another one in the grip area; the second one would be used to cancel out the movement of users' head and body, allowing the first one to effectively operate in a mouth-relative coordinate system.)
Maybe not from brushing one tooth but brushing the whole mouth you'd get a pretty good picture I'd say. The app would justify itself if it did give you a rough map of how you brushed your teeth and suggest areas that you're missing/if it's being done incorrectly.
How does it even have a census of your teeth?
Some people have wisdom teeth, while other people don't.
Some people have been on the losing end of a bar fight with carneys, and some people haven't.