Michigan Compiled Laws, Chapter 333. Health § 333.16641

Sec. 16641. (1) A dentist shall not use the services of a dental laboratory without furnishing a written work authorization to the dental laboratory and a carbon copy to the patient for constructing, repairing, or altering prosthetic dentures, bridges, orthodontic or other appliances, or structures to be used as substitutes for or as a part of human teeth or jaws or associated structures, or for the correction of malocclusions or deformities.

(2) A dentist shall retain a written work authorization furnished to a dental laboratory or a copy of the authorization for not less than 3 years and allow the board, its agents, or employees to inspect the file of written work authorizations or copies.