Some schools confer a DDS (Doctor of Dental Surgery) degree and others choose to award a DMD (Doctor of Dental Medicine) degree instead. The training the dentist gets is typically similar, but the name of the degree granted is different.
DDS was the typical degree for a dentist until Harvard University added a dental school in 1867. The degrees granted by Harvard are in Latin. The Latin translation of DDS would have been CDD. They made the degree Dentariae Medicinae Doctor, or DMD.
So, it comes down to where the dentist attended dental school. It is not a distinction based on the quality of the degree. Regardless of the name of the degree, you should visit your dentist regularly. If you don't have a dentist, find one today.