US health insurance tends to distinguish based on the location whether it's "dental" or "medical": if an infection sends you to the hospital, then it's medical, but if you go to the dentist to get it fixed, then it's dental. Typically the latter wouldn't get covered by health insurance regardless of severity.

There are some miscellaneous oddities; for example, if you visit a dentist and have antibiotics prescribed, typically the visit won't be covered (it's a dentist so counts as dental), but the antibiotics will be covered (they're a medical prescription).