The recommended dose of Tylenol is 4000mg a day but that's not the maximum dose. It's commonly prescribed at 2g four times a day (8g/day) in the hospital setting for baseline pain control and that is still considered safe.
There is however a very small percentage of people that can develop liver failure at such doses but it is very rare. Anyay you shouldn't be taking any painkillers longer than a few days without seeing a doctor, or in this case a dentist.







