The UK's dental care is also not really covered by the NHS beyond a few emergency procedures, and even when it is (assuming you can get onto an NHS dentist's register) it costs a significant amount of money (70+ for checkup and dental work) once you turn 18, so I can imagine that most people just don't bother.

I've already resigned myself to getting most of my teeth removed or replaced, as painful as that is, because I spent years without dentist cover thanks to COVID and generally refusing to spend the costs on checkups (as bad an idea that was)