The following functions may be performed by a registered dental hygienist, in addition to those authorized pursuant to Sections 1908 to 1914, inclusive:
(a) All functions that may be performed by a registered dental assistant.
(b) All persons holding a license as a registered dental hygienist, registered dental hygienist in alternative practice, or registered dental hygienist in extended functions as of December 31, 2005, are authorized to perform the duties of a registered dental assistant specified in this chapter. All persons issued a license as a registered dental hygienist, registered dental hygienist in alternative practice, or registered dental hygienist in extended functions on or after January 1, 2006, shall qualify for and receive a registered dental assistant license prior to performance of the duties of a registered dental assistant specified in this chapter.