Hi, I had arthroscopic TFCC repair on my dominant hand 6 weeks ago. I'm wondering when I'll be allowed to work again (I'm a dentist).?

TFCCrepair varies. At times findings seen arthroscopicaly such as small tears may not be relevant to function, while at others they are vitally important.and immobilzaiotn is needed Ask your surgeon about this and the discussion regarding options for light duty should follow. The condition of cartilage, arthritis and surrounding tissues is equally important as are your repair.
2-3 months. After a TFC repair, it takes about 6 weeks for the healing to be complete (assuming you were casted after surgery). Then you need to go through therapy to regain motion and strength in your wrist. That can take an additional 6 weeks or so, although light activity is usually ok after the initial 6 weeks.