Section 6. A subscription certificate shall be issued by a dental service corporation to each non-group subscriber. No subscription certificate shall be issued unless the commissioner shall have approved in writing the form of certificate nor unless it contains in substance the following provisions:
(a) A statement of the dental service to be paid for by the corporation and if any dental service is excepted, a statement of such exception.
(b) A statement of the duration of the agreement and of the terms and conditions upon which it may be extended, renewed, revised, cancelled or otherwise terminated.
(c) A statement of the period of grace which will be allowed for making any payment due from the subscriber under the contract, which in any event shall not be less than ten days.
(d) A statement that any child who is mentally or physically incapable of earning his own living who is eligible for services by membership of his parent under a family contract shall be eligible under the membership of his parent as a member of such family contract so long as he continues to be mentally or physically incapable of earning his own living, without any limitation as to age, subject, however, to such rules and regulations, premiums or additional premiums as the commissioner of insurance may approve.