Wash. Rev. Code § 18.32.020
A person practices dentistry, within the meaning of this chapter, who (1) represents himself or herself as being able to diagnose, treat, remove stains and concretions from teeth, operate or prescribe for any disease, pain, injury, deficiency, deformity, or physical condition of the human teeth, alveolar process, gums, or jaw, or (2) offers or undertakes by any means or methods to diagnose, treat, remove stains or concretions from teeth, operate or prescribe for any disease, pain, injury, deficiency, deformity, or physical condition of the same, or take impressions of the teeth or jaw, or (3) owns, maintains, or operates an office for the practice of dentistry, or (4) engages in any of the practices included in the curricula of recognized and approved dental schools or colleges, or (5) professes to the public by any method to furnish, supply, construct, reproduce, or repair any prosthetic denture, bridge, appliance, or other structure to be worn in the human mouth.
The fact that a person uses any dental degree, or designation, or any card, device, directory, poster, sign, or other media whereby he or she represents himself or herself to be a dentist, shall be prima facie evidence that such person is engaged in the practice of dentistry.
X-ray diagnosis as to the method of dental practice in which the diagnosis and examination is made of the normal and abnormal structures, parts, or functions of the human teeth, the alveolar process, maxilla, mandible or soft tissues adjacent thereto, is hereby declared to be the practice of dentistry. Any person other than a regularly licensed physician or surgeon who makes any diagnosis or interpretation or explanation, or attempts to diagnose or to make any interpretation or explanation of the registered shadow or shadows of any part of the human teeth, alveolar process, maxilla, mandible or soft tissues adjacent thereto by the use of X-ray is declared to be engaged in the practice of dentistry, medicine, or surgery.
The practice of dentistry includes the performance of any dental or oral and maxillofacial surgery. "Oral and maxillofacial surgery" means the specialty of dentistry that includes the diagnosis and surgical and adjunctive treatment of diseases, injuries, and defects of the hard and soft tissues of the oral and maxillofacial region.
RCW 18.32.020