CDT codes

What are CDT codes?

CDT codes (Current Dental Terminology) are standardized five-digit billing codes, beginning with the letter D, published and maintained by the American Dental Association. Every dental procedure submitted on an insurance claim uses one or more CDT codes. The code tells the carrier exactly what procedure was performed, allowing the plan to look up the applicable service category (preventive, basic, major), the coinsurance rate, any waiting period, and the allowed amount in its fee schedule. Plans do not cover 'dental care' in the abstract, they cover or deny specific CDT codes as listed in their Schedule of Benefits.

How it works

Your dentist selects the appropriate CDT code(s) for each procedure and includes them on the ADA claim form submitted to the carrier. The carrier's adjudication system maps each code to its coverage rules: Is this a covered code? What tier (preventive/basic/major) is it? Has the waiting period elapsed? Has the member met the frequency limit for this code? What is the allowed amount? The system calculates the plan payment and member responsibility based on these rules and issues an Explanation of Benefits.

What to watch out for

• ⚠Downcoding is a claims practice where the carrier substitutes a less expensive CDT code for the one submitted, reducing the allowed amount and increasing your coinsurance obligation. If you receive an EOB that references a different code than your dentist submitted, ask your dentist to file an appeal with the original documentation.
• ⚠Some codes are subject to frequency limits. D1110 (adult prophy) is typically limited to two per calendar year. Submitting a third generates an automatic denial regardless of clinical necessity. Periodontal maintenance (D4910) is a different code with different frequency rules, used when cleanings are prescribed as disease treatment, not prevention.