Section 23O. No person shall hold himself out as an occupational therapist or as an occupational therapy assistant or as being able to practice occupational therapy or to render occupational therapy services in the commonwealth unless he is licensed in accordance with section twenty-three B. No person not so licensed may use in connection with his name or place of business the letters, ”O.T.R.”, or ”C.O.T.A.”, or any other words, letters, abbreviations, or insignia indicating that he is an occupational therapist or occupational therapy assistant.