If you are HIV+ or are a carrier of hepatitis B or C, there is no reason why your dentist should not continue to treat you in a normal way. The only reason this would change is if you develop AIDS, when your treatment may need to be modified - because AIDS can make you more susceptable to infection. Equipment in dental practices has to undergo an extremely high level of sterilisation, to minimise any chance of cross-infection. The only reason your dentist may refer you is if you have a condition that they feel would be better treated by a specialist, just as they would with any patient, regardless of HIV or hepatitis status.
Always tell your dentist of any medical condition, including HIV, AIDS, or hepatitis B or C. Your privacy will be respected.