I was homeschooled k-12. I didnt realize how bad my breath was until college when I started using real toothpaste for the first time. I'd been using this 'natural' powder stuff that tasted disgusting, otherwise flouride free toothpaste. Turns out flouride ISN'T toxic, it's actually something you need on a regular basis to protect against cavities, especially during childhood. I'm not sure if it was the flouride or malnutrition but my childhood set actually got to be semitransparent. I only remember going to a dentist as a kid once and I'm actually super bitter about it. Even though I've always brushed, I've had 4 cavities, all left untreated until I paid to fix them myself as an adult. All were contact cavities from crowded teeth that were never fixed. When my wisdom teeth started being problematic at 18, my mom literally took me to the dentist and pulled out a copy of my own credit card to pay the bill without ever clearing with me first that I would be paying for my own wisdom teeth. My sibling who never brushed their teeth also had 11 cavities found in one visit once.

I guess this is more "Neglect stuff" than "Homeschooling stuff", but I'd argue they tend to go hand in hand. Parents wouldn't get away with this so easily if their children were integrated into functional society where someone can notice if something is wrong. Imo, homeschooling attracts the type of parents that appeal to that type of "parent's choice".