A form of dental cost sharing in a dental insurance plan that requires the member to pay a fixed dollar amount for each visit to a dentist or for a specific service. This fee is pre-set; it will be specified in your dental insurance policy. It also may be listed on your dental insurance card. Most PPO dental plans are co-insurance-based; however, some plans use co-payments in lieu of co-insurance or will have an office visit co-payment in addition to co-insurance.