Depends a lot on the country, but (AFAIK) dental expenses are not fully covered by national health services.
In Sweden, they are free until the year of your 24th birthday, then they are privately paid.
There’s a quota, though, that’s contributed by healthcare, to ease the higher cost treatments:
Note that reimbursement is calculated on standardized “reference prices” which can differ substantially from the actual price you pay to the dentist.
OTOH, in Italy, only basic dental healthcare (fillings, checks, etc.) is provided to child 0-14 and none later, unless you have disabilities or financial vulnerabilities (note: this is a very condensed summary, rules are quite complicated…).
