From OCR through the ADA, Dental labs do NOT need to sign a BAA for HIPAA:
Dental laboratories aren’t required to sign business associate agreements before dental practices share protected health information for treatment of an individual, according to the U.S. Health and Human Services Office for Civil Rights, because a dental laboratory meets the Health Insurance Portability and Accountability Act’s definition of a “health care provider.”
This is good to know. When I read the rules my interpretation was that labs were exempt from Business Associate Agreements as what they provide clearly falls in the realm of patient treatment. Nevertheless some HIPAA consultants disagreed and advised dentists to get a BAA from their dental labs. It is nice to get clarification.