No ! HIV is not contracted from a dental clinic. In the entire history of HIV/AIDS spread over 3 decades and tens of million infected people, there is only one reported "questionable" case and experts still debate on that. What you should be looking for, is the sterilization practices at the dental clinic you choose, not because of HIV but because of Hepatitis, which is possible from an unsterilized equipment. In my country, we have seen a few cases where patients caught hepatitis from dental clinics.