After recently re-watching the Harry Potter series, I noticed that the Weasleys' clock shown in The Chamber of Secrets has a location setting of "dentist" for the family members. However, during the dinner party in The Half Blood Prince, Professor Slughorn seems to be completely unfamiliar with the concept of dentistry. Is this just an oversight by the script writers, or do some wizarding families have different hygiene practices? Could it possibly be explained due to the Weasleys' exposure to muggle oral care from Mr. Weasley's job at the Ministry?
There does appear to be dentistry in the wizarding world, just not the kind of 'hack and smash with a pair of rusty pliers' dentistry that we muggles are used to. Notably, the practice seems to be part of the general medical care offered by nurses.
If a wizard damaged their tooth, they would be well advised to visit a doctor or nurse skilled in the regrowing and straightening of teeth. At that point, the clock would turn to "DENTIST".
In Harry Potter and the Goblet of Fire, Hermione visits Madame Pomfrey and has her teeth 'fixed':
‘Hermione,’ said Ron, looking sideways at her, suddenly frowning, ‘your teeth …’
‘What about them?’ she said.
‘Well, they’re different … I’ve just noticed …’
‘Of course they are – did you expect me to keep those fangs Malfoy gave me?’
‘No, I mean, they’re different to how they were before he put that hex on you … they’re all … straight and – and normal sized.’
Hermione suddenly smiled very mischievously, and Harry noticed it too: it was a very different smile to the one he remembered.
‘Well … when I went up to Madam Pomfrey to get them shrunk, she held up a mirror, and told me to stop her when they were back to how they normally were,’ she said. ‘And I just … let her carry on a bit.’ She smiled.
As far as the film series is concerned, although Prof. Slughorn may be personally unaware of dentistry, there's a sign in Diagon Alley advertising a "Surgical and Dental Operator" visible in Harry Potter and the Philosopher's Stone, clearly indicating that the profession is at least slightly known in the wizarding world.