60. Where a dental hygienist states his professional fees in an advertisement, he shall do so in a manner that is understandable to persons having no special knowledge of dentistry, and he shall
(1) set fixed prices;
(2) specify the nature and extent of the services included in the prices;
(3) indicate whether the expenses and other charges are included in the prices; and
(4) indicate whether additional services might be required, for which an additional amount might be charged.
Any such price shall remain in effect for a minimum period of 90 days after it is last broadcast or published. However, a dental hygienist may agree with a client on a price lower than the price broadcast or published.