215 ILCS 115/2
Any employer, group or organization that pays or contributes to the premium of a group health insurance plan or a dental service plan corporation which provides dental coverage to eligible employees or members of such employer, group or organization only upon the condition that such employees or members obtain dental services from a list of dentists or groups of dentists approved by the insurer or dental service corporation shall provide an alternative plan whereby the employees or members may obtain services from dentists not on the list approved by such insurer or dental service corporation. Where an employee or member elects such alternative plan, the employer, group or organization shall contribute the same dollar amount toward the payment of dental services under the alternative plan as such employer, group or organization would have contributed under the original plan. Nothing in this Section requires the commingling of costs and claims experience between the two plans.
215 ILCS 115/2