Final answer:
The claim that a Registered Dental Hygienist (RDH) in California cannot perform the duties of a Registered Dental Assistant (RDA) without an RDA license is false, as the RDH scope of practice is separate and they must have the necessary RDA license to perform RDA-specific duties.
Therefore, this statement is false.
Step-by-step explanation:
The statement that an individual who becomes licensed as an RDH (Registered Dental Hygienist) in California on or after January 1, 2006, may no longer perform the duties in the scopes of practice of an RDA (Registered Dental Assistant) unless they also hold an RDA license is False. An RDH has a separate scope of practice and is not allowed to perform the functions specific to an RDA without the necessary RDA license, regardless of the date of their licensure. However, an RDH licensed in California is allowed to perform overlapping duties that are within both the RDH and RDA scopes of practice, as well as those procedures specifically permitted to RDHs under their own licensure.