Section 50. A person shall be deemed to be practicing dentistry if he holds himself out as being able to diagnose, treat, operate or prescribe for any disease, pain, injury, deficiency, deformity or other condition of the human teeth, alveolar process, gums or jaws, and associated parts, intraorally or extraorally, or if he either offers or undertakes by any method to diagnose, treat, operate or prescribe for any disease, pain, injury, deficiency, deformity or other condition of the same; or if he, except on the written prescription of a registered dentist and by the use of impressions made by a registered dentist, directly or indirectly by mail, carrier, personal agent, or by any other method, supplies, constructs, reproduces, relines, repairs, adds or directs the application of any substance, of a durable nature, to dentures, bridges, appliances or other structures to be used and worn as substitutes for natural teeth or solicits or advertises, except as permitted in section fifty-two A, to supply, construct, reproduce, repair, reline, add or direct the application of any substance, of a durable nature, to dentures, bridges, appliances or other structures to be used and worn as substitutes for natural teeth; or if he places such substitutes in the mouth or adjusts the same; or if he, except on the written prescription of a registered dentist, observes a patient's natural dentition for purposes of matching coloration or other aesthetic characteristic to aid in the fabrication or repair of a prescribed restorative appliance.

Every complete upper and lower denture or removable dental prosthesis, fabricated by a registered dentist or fabricated pursuant to such dentist's written prescription order, shall be marked with the name or social security number, or both, of the patient for whom the prosthesis is intended. Such markings shall be applied during fabrication and shall be permanent, legible and cosmetically acceptable. The exact location of the markings and method used to apply or implant the markings shall be determined by the dentist or dental laboratory fabricating the prosthesis. If in the professional judgment of the dentist, this full identification is not possible, the name or social security number may be omitted.

Any removable dental prosthesis in existence prior to the effective date of this act, which was not marked in the manner heretofore described, shall be so marked at the time of any subsequent rebasing or duplication.