The Department of Public Health may, on request, furnish dental services for children in areas of the state where adequate dental service is unavailable. Such dental service shall be furnished free of charge to all children where the cost of necessary service would be a financial hardship to their parents. Such dental service may be furnished to children of parents who are financially able to pay part or all of the cost of dental services received by their children. Said department is authorized to charge for dental service in such cases, but in no case more than the actual cost of such service and materials.