How Many CDT Codes Are There, and Which Ones Matter

Ask how many CDT codes are there and the honest answer is a moving target: roughly 800 procedure codes in the current edition, spread across twelve categories of service, revised every January 1. Published counts differ because some lists fold in recently deleted codes and some count the unspecified "by report" codes separately. The total matters far less than two things you control: whether your practice software is still carrying codes the ADA retired, and whether the handful of codes that carry most of your production are coded the way the plan reads them.

The twelve categories of service

Every CDT code is five characters, a capital D followed by four digits, and the first digit tells you the category. This is the map worth pinning up.

Two structural details that come up constantly. First, implant services and fixed prosthodontics share the D6000 block but are separate categories, split at D6200, which is why a plan can cover one and exclude the other. Second, every category ends with an unspecified "by report" code such as D2999 or D9999. Those are for procedures with no assigned code, they require a narrative, and they are among the most abused codes in dentistry. If you are using one routinely, a real code almost certainly exists.

How often are CDT codes updated?

Once a year, effective January 1, on a cycle that runs longer than most practices realize.

Code change requests are submitted to the ADA, the Code Maintenance Committee reviews and votes on them in the spring, and the approved set is published in the fall for use starting the following January 1. As of this writing, requests are due months ahead of that spring vote, so a code requested today is unlikely to be billable for over a year. Confirm current dates with the ADA.

Two consequences that cost money every January:

There is no grace period. A code deleted on December 31 is rejected on January 1. Payers are not obliged to translate a retired code into its replacement, and most do not.

Date of service governs, not submission date. A procedure performed on December 28 is billed with the code that was valid on December 28, even if the claim leaves your office in February. Practices that update their software on January 2 and then batch out December's backlog with January's codes generate a week of avoidable rejections.

What are the new 2026 CDT codes?

Every annual update arrives as four things, not one: new codes, revised codes, deleted codes, and editorial or policy changes to the manual. Carrier summaries of the 2026 update have described roughly thirty additions, about a dozen revisions and a handful of deletions. Treat any third party count as directional and confirm the list against the ADA's own publication.

The revisions are the ones that ambush people. A revised nomenclature or descriptor can change what documentation a code requires while the number itself stays the same, so nothing in your software looks different and your denial rate moves anyway. Read the revision list, not just the additions.

A workable January changeover, in order:

1. Pull last year's production report and list every distinct code you billed. That is your exposure.
2. Cross reference it against the deletion list. Any match is a hard stop that needs a replacement code mapped in your software before the first claim of the year.
3. Read the revision list against that same production list. Where a descriptor changed, update the clinical note template, not just the code.
4. Treat new codes as unfunded until proven otherwise. A code existing in CDT does not mean any plan has written a benefit for it. New codes routinely sit without an assigned benefit for a year or more.
5. Send a predetermination on any new, high dollar code before you schedule the case. The same logic applies to elective work generally, which our guide to getting a predetermination for dental veneers approved works through in detail.

That last point is where new codes and denials meet. Graft and regenerative codes are a standing example, since a technically correct code with thin documentation still gets refused. See why a dental bone graft claim gets denied for how that plays out line by line.

What is the difference between the CDT codes D0180 and D0120?

These two get confused more than any other pair in the diagnostic block, and the difference is documentation, not opinion.

Risk factors that support D0180 include tobacco use and diabetes, alongside the clinical findings. The code is legitimate and underused in practices that do thorough periodontal screening, and indefensible in practices that submit it without charting.

On frequency: most plans pool D0120, D0150 and D0180 into one evaluation allowance, commonly quoted as two per benefit year, but that pooling and the count are plan level decisions made by the employer group. Verify the shared frequency for the specific plan rather than assuming a carrier handles it uniformly, and record the answer with the date and reference number.

What is the difference between CPT and CDT codes?

Different maintainers, different forms, different logic for getting paid.

One detail that surprises people: the CDT codes are incorporated into HCPCS Level II as the D codes, which is how they appear in federal program coding contexts. CDT is also the HIPAA designated code set for dental services, so it is not merely an ADA convention.

The practical overlap is cross coding, where a dental procedure with a medical basis goes to the medical plan instead. Sleep apnea appliances, biopsies, trauma and temporomandibular joint therapy are the usual candidates. Our deeper comparison of CDT and CPT codes in dentistry covers the translation, and medical billing for TMJ treatments in a dental office covers the highest volume case, including the diagnosis coding that finding ICD-10 codes for TMJ disorders walks through.

Where the official list lives, and why free PDFs cost money

The CDT Code is copyrighted by the ADA and licensed through its publications. There is no complete official free download, which is why searches for a free CDT PDF turn up unofficial lists, and why those lists are so often one or two editions stale. Submitting a code that was deleted three years ago produces a rejection that looks like a payer problem and is not.

Diagnosis codes are the opposite case. ICD-10-CM is published by federal agencies and is genuinely free to look up, so paying a subscription for basic ICD-10 lookups is money burned, as our guide to free diagnostic code lookups explains. Do not generalize that to CDT. Buy the manual or license the feed your software uses.

Curo checks every claim line against the current code set before it leaves the practice, so a retired code or a mismatch between the code and the documentation surfaces at submission rather than three weeks later on a rejection report. You can see how that scrubbing works on the claims automation page.

The count that actually runs your practice

Roughly 800 codes exist. Your practice does not bill 800 codes, and the real number is the useful one.

Pull a production report for the last twelve months, group by procedure code, and sort by total production. Most offices find the list far shorter than they expected, and the top slice accounts for the overwhelming majority of what they collect. That short list is what deserves an annual audit: correct code, correct descriptor, documentation template that matches what the descriptor now says, and a verified frequency rule for each of your top plans.

Auditing 800 codes is a project nobody will finish. Auditing the codes that pay your rent is an afternoon, once a year, in the first week of January.