Texas Insurance Code - INS § 1203.053. Certain Coordination of Benefits Provisions Prohibited

(1) a provision of the policy excludes or reduces the payment of benefits for dental expenses to or on behalf of an insured;

(2) the reason for the exclusion or reduction is that dental benefits are payable or have been paid to or on behalf of the insured under another insurance policy;  and

(3) the exclusion or reduction would apply before the full amount of the dental expenses incurred by the insured and covered by both policies have been paid or reimbursed or the full amount of the applicable policy limit of the policy containing the exclusion or reduction is reached.