CDT Codes: A Guide to Dental Billing and Coding

Every dental claim is built on CDT codes. CDT, the Code on Dental Procedures and Nomenclature, is the code set the American Dental Association maintains for reporting dental services, and it is the HIPAA standard for dental claims. Get the code right and the claim has a chance. Get it wrong and the claim is denied, downgraded, or paid at a rate that never covered the work. This guide explains how CDT codes are organized, which codes practices bill most, and where dental coding most often goes wrong.

How CDT Codes Work

Each CDT code is five characters: the letter D followed by four numbers. The code identifies a procedure, and its descriptor defines exactly what that procedure includes. The ADA updates the code set every year, and each new version takes effect on January 1. New codes are added, some are revised, and some are deleted, so a code that was correct last year can be rejected this year. Practice management software usually updates its code tables, but fee schedules, templates, and staff habits often lag behind.

CDT codes are for dental services billed to dental plans. Medical plans use CPT and HCPCS codes for procedures and ICD-10-CM codes for diagnoses. When a dental procedure is billed to a patient’s medical insurance, it has to be coded in the medical code sets instead, which we cover below.

The 12 CDT Code Categories

Code range	Category	Examples
D0100–D0999	Diagnostic	Oral evaluations, radiographs, tests
D1000–D1999	Preventive	Cleanings, fluoride, sealants, space maintainers
D2000–D2999	Restorative	Fillings, crowns, buildups
D3000–D3999	Endodontics	Root canals, pulp treatment
D4000–D4999	Periodontics	Scaling and root planing, periodontal maintenance, gum surgery
D5000–D5899	Prosthodontics, removable	Dentures and partials
D5900–D5999	Maxillofacial prosthetics	Prostheses for facial and oral defects
D6000–D6199	Implant services	Implant placement and implant-supported restorations
D6200–D6999	Prosthodontics, fixed	Bridges
D7000–D7999	Oral and maxillofacial surgery	Extractions, surgical procedures
D8000–D8999	Orthodontics	Limited and comprehensive orthodontic treatment
D9000–D9999	Adjunctive general services	Palliative treatment, anesthesia, consultations, occlusal guards

CDT Codes Practices Bill Most Often

The descriptions below are short summaries. Always check the current CDT manual for the full descriptor before billing.

Diagnostic

• D0120: periodic oral evaluation for an established patient.
• D0140: limited oral evaluation focused on a specific problem.
• D0150: comprehensive oral evaluation for a new or established patient.
• D0180: comprehensive periodontal evaluation.
• D0210: intraoral complete series of radiographic images.
• D0220 and D0230: periapical images, first and each additional.
• D0274: bitewings, four images.
• D0330: panoramic radiographic image.

Preventive

• D1110 and D1120: prophylaxis for adults and for children.
• D1206: topical fluoride varnish.
• D1351: sealant, per tooth.

Restorative

• D2140: amalgam filling, one surface.
• D2391: resin-based composite filling, one surface, posterior.
• D2740: porcelain or ceramic crown.
• D2750: porcelain fused to high noble metal crown.
• D2950: core buildup, including any pins when required.

Endodontics

• D3310, D3320, and D3330: root canal therapy on an anterior tooth, a premolar, and a molar.

Periodontics

• D4341 and D4342: scaling and root planing per quadrant, for four or more teeth and for one to three teeth.
• D4346: scaling in the presence of generalized moderate or severe gingival inflammation, full mouth, after an oral evaluation.
• D4355: full mouth debridement, so that a comprehensive evaluation and diagnosis can be done on a later visit.
• D4910: periodontal maintenance after active periodontal therapy.

Implants, Surgery, Orthodontics, and Adjunctive Services

• D6010: surgical placement of an endosteal implant body.
• D7140: extraction of an erupted tooth or exposed root.
• D7210: surgical extraction of an erupted tooth that requires removing bone or sectioning the tooth.
• D8080: comprehensive orthodontic treatment of the adolescent dentition. Our orthodontic billing page covers the rest of the D8000 codes.
• D9110: palliative treatment of dental pain, per visit.
• D9230: inhalation of nitrous oxide.
• D9944: hard occlusal guard, full arch.

Where Dental Coding Goes Wrong

• Prophylaxis, D4346, or scaling and root planing. D1110, D4346, and D4341/D4342 describe different conditions. The choice has to match the evaluation and the periodontal charting in the record, and plans often ask for that charting when D4346 or scaling and root planing is billed.
• Evaluations billed too often. Plans limit how often periodic, comprehensive, and periodontal evaluations are paid. Billing D0150 for an established patient who does not meet the plan’s rules is a common denial.
• Buildups without support. D2950 is often reviewed. Plans may ask for radiographs or a narrative showing why the buildup was needed to retain the crown.
• Missing attachments and narratives. Crowns, scaling and root planing, buildups, and many surgical procedures commonly need radiographs, periodontal charts, photos, or a narrative. A claim without them often stalls or is denied. See our guide to dental insurance claims processing.
• Outdated codes. Codes deleted or revised in the annual update will reject if fee schedules and templates were not updated on January 1.
• Coding the procedure, not the documentation. The code has to describe what the clinical note supports, not what was planned.

Downgrades and Plan Limitations

A correctly coded claim can still pay less than expected because of how the plan is written. These limits explain many of the “underpayments” dental practices see:

• Frequency limits: plans cap how often a service is covered, such as cleanings, bitewings, full series radiographs, and fluoride.
• Alternate benefit clauses: many plans pay a posterior composite filling at the amalgam rate, or a crown at the rate of a less costly alternative. The claim is paid, but at a lower allowance.
• Missing tooth clauses: some plans will not pay to replace a tooth that was missing before coverage began.
• Waiting periods and age limits: major services, orthodontics, sealants, and fluoride often have waiting periods or age limits.

Most of these can be found before treatment with a full benefits breakdown rather than a basic eligibility check. Our dental insurance verification services page covers what that breakdown should include.

When Dental Procedures Are Billed to Medical Insurance

Some dental procedures are covered by a patient’s medical plan, such as certain oral surgery, treatment after trauma, biopsies, and oral appliances for sleep apnea. These claims are coded with CPT or HCPCS procedure codes and ICD-10-CM diagnosis codes, submitted on the CMS-1500 medical claim form, and usually need documentation of medical necessity. This is often called cross coding. It is a different process from dental billing, and a dental code on a medical claim will not be paid. Our oral surgery billing services page covers how medical and dental claims work together.

Keeping Coding Accurate

1. Update fee schedules, templates, and code tables every January when the new CDT version takes effect.
2. Code from the clinical note, and make sure the note supports the descriptor.
3. Attach radiographs, charts, and narratives when a plan requires them, instead of waiting for a request.
4. Check frequency limits, waiting periods, and alternate benefit clauses before treatment.
5. Track denials by code and by plan, so the same problem does not repeat.

How Maximum Billing Helps

Maximum Billing handles dental billing and coding for practices in twelve states, working inside Eaglesoft, Dentrix, Dentrix Ascend, and Open Dental. We review coding against the record, attach the documentation plans ask for, follow up on every unpaid claim, and appeal downgrades that were paid wrong. See our dental billing services, our guide on how to choose a dental billing company, or our dental credentialing services.

Frequently Asked Questions

What does CDT stand for?

Code on Dental Procedures and Nomenclature. It is maintained by the American Dental Association and is the HIPAA standard code set for dental procedures.

How often do CDT codes change?

Every year. Each new version takes effect on January 1, with codes added, revised, and deleted.

What is the difference between CDT and CPT codes?

CDT codes report dental procedures to dental plans. CPT codes report medical procedures to medical plans. A dental procedure billed to medical insurance has to use CPT or HCPCS codes with ICD-10-CM diagnosis codes.

Why did a plan pay less than the fee for a correctly coded procedure?

Usually because of a plan limitation, such as an alternate benefit clause, a frequency limit, or the plan’s maximum allowable fee. A full benefits check before treatment shows most of these in advance.