(e) It is unlawful for any dental laboratory either directly or indirectly:

1. (1) To advertise that it is engaged in the business of performing dental laboratory services;
2. (2) To advertise it performs dental laboratory services for members of the public;
3. (3) To advertise a price for the performance of dental laboratory services; or
4. (4) To advertise techniques used or materials employed by it in the performance of dental laboratory services: Provided, That this subsection does not prevent dental laboratories from advertising in dental journals or in other professional dental publications or from communicating directly to a dentist and other dental practitioner or from listing the dental laboratory in business and telephone directories if the business and telephone directory announcements are limited to name, address and telephone number and do not occupy more than the number of lines necessary to disclose the information, or from displaying the trade name and address of the dental laboratory on the door of its place of business or on name plates or door plates exhibited on the interior or exterior of the place of business.