to log how well you're brushing your teeth, so it can advise you on how to brush your teeth better, so you can have better teeth and not have to see the dentist. it's a late stage technology thing.
I wasn't born with an innate ability to know how to brush my teeth or how to shave (my electric razor also has an app), I had to learn how. If the devices I use can tell that I'm using them wrong, and there's a better way to do things, it's nice to have it tell me.
Except brushing is just one piece of an overall oral health. Flossing is another thing. Then you got your diet which plays a great role in your teeth health. How would one tracking app know all of this?
Tracking the temperature and time of cooking is only one part about grilling meats. There's still cutting the meat, ingredients in the rub, applying the rub, the cooldown, the final slicing, and so much more. Why bother having an app-connected remote thermometer if it can't do all of these things?
I don't care for an app-connected toothbrush personally. But suggesting that just because it can't keep track of your diet overall means it can't possibly give any insights in health is overly reductive. A workout tracker app can't keep track of your food intake, but that doesn't mean it can't help the user be healthier.
When I was a child we got taught that at school. They had a large model of the human mouth and an oversized toothbrush. Perhaps that's too low tech for folks nowadays, I don't know.
Apart from the I go to the dentist 2-3 times a year, they do a great job telling me what area of my mouth I need to focus on. A toothbrush wouldn't really be able to give me that info anyway.
The idea is to help focus brushing on specific teeth or quadrants, and it uses Bluetooth to know when the brush is on or off. Maybe it signals when you push too hard and the brush pauses for a second as well.
To my knowledge it does not know where you are in your mouth when brushing (positioning via accelerometer/gyroscope), so a synchronized start would likely give similar results.
And if we were in an alternate universe where we had reason to believe that the app did this analysis offline and never sent the data off to be sold to who-knows-who, that would be fine.
I wasn't born with an innate ability to know how to brush my teeth or how to shave (my electric razor also has an app), I had to learn how. If the devices I use can tell that I'm using them wrong, and there's a better way to do things, it's nice to have it tell me.