From WHY DO RABBITS' TEETH NEVER STOP GROWING?:
A rabbit's teeth grow 3-5 inches annually. From the below quotes we can see that a rabbit's teeth grow very fast.
The extensive chewing and gnawing that rabbits regularly engage in
balances the perpetual tooth growth. If a rabbit’s teeth were not
open-rooted, they would wear down very quickly, eventually rendering
chewing such dietary requirements extremely difficult.
In the wild, rabbits have unlimited access to the vegetation that
keeps their growing teeth under control. Pet rabbits are much more
limited and require continuous supply of timothy hay.
Because their teeth grow so fast and their teeth engage with fibrous vegetation that normally cleans teeth, concerns for Dental Caries are very low. But that does not mean impossible, I have heard nothing indicating Rabbit rates of cavities, but because their teeth grow out and the damaged teeth would be gone the risk would be low.
This post supports my thoughts that Rabbit Cavities are basically impossible.
Like the post says Cavities are unlikely because of teeth growth rate, but damage and abscesses to the jaw are more likely, as are ingrown teeth that don't erupt properly.