A provision of a dental benefit program by which the beneficiary shares in the cost of covered services, generally on a percentage basis. The percentage of a covered dental expense that a beneficiary must pay (after the deductible is paid). A typical coinsurance arrangement is one in which the third party pays 80% of the allowed benefit of the covered dental service and the beneficiary pays the remainder of the amount due the dentist. Percentages vary and may apply to table of allowance plans; maximum allowable benefit plans and direct reimbursement programs.