Most kids can brush their own teeth without supervision after 7 years old.
I would supervise the child until at least 8 years old when they are brushing their teeth as they may swallow small amounts of toothpaste or they may decide to never brush their teeth at all.
My mom had to supervise me brushing my teeth until I was 12 years old because I would sometimes not want to brush my teeth.
If your child swallows a small amount of toothpaste then there's nothing you have to do.
Swallowing a small amount of toothpaste is not harmful and will only likely cause a slight stomach ache that will go away within a few hours or so.
If the child swallowed more than a small amount of toothpaste then take them to the emergency room or a walk in clinic.
But for small amounts of toothpaste there's nothing you can really do or need to do.
If you happen to swallow a bit of toothpaste while brushing your teeth then nothing bad will happen except maybe a stomach ache.
However if you swallow too much toothpaste then you would get fluoride poisoning but it would take swallowing a whole tube of toothpaste to get sick enough to cause severe illness.
A bit of toothpaste should not cause any health issues but avoid swallowing the toothpaste because it's not meant to be swallowed.
Brush your teeth and then use some water to rinse the toothpaste out of your mouth and spit the toothpaste out.
It can be dangerous to swallow too much toothpaste.
However if you happen to swallow a tiny put of toothpaste or swallow the small amount of toothpaste that you use for brushing your teeth then nothing bad should happen.
I have swallowed some toothpaste before and the worst that happened to me was I got a stomach ache for a day until the toothpaste left my stomach.
You can get fluoride poisoning though if you do swallow too much toothpaste so just do your best to avoid swallowing toothpaste.
Swallowing toothpaste could make you sick and it's not meant to be swallowed.
Make sure you teach your kids if you have any to spit out toothpaste and not swallow it and always supervise kids under 7 years old with brushing their teeth to make sure they don't swallow the toothpaste.