Mont. Code Ann. § 37-4-502

No person, firm, or corporation engaged in the business of constructing, altering, or repairing bridges, crowns, dentures, other prosthetic appliances, surgical appliances, or orthodontic appliances may advertise the services, technique, or materials to the general public by means of advertisements in public newspapers, magazines, or by radio, television, display advertisements, or by any other means except advertisements in professional or trade papers, trade journals, trade directories, trade periodicals, trade magazines, and listings in business and telephone directories limited to name, address, and telephone number, which may not occupy more than the number of lines necessary to disclose the information; nor may a person, firm, or corporation so engaged in any way directly solicit the patronage of the general public.