ICD-10-CM on a dental claim: the K00 to K14 block, the codes dentists actually reach for, and the October 1 update that is free to download

What it says#

ICD-10-CM is the diagnosis half of coding. A CDT code says what you did; an ICD-10-CM code says what was wrong. The set is the clinical modification of the World Health Organization's ICD-10, which WHO owns and publishes; NCHS states that WHO authorized it to develop ICD-10-CM for use in the United States and that all modifications must conform to WHO's structure and conventions.

The legal hook is the same rule that adopts the CDT Code. 45 CFR 162.1002(c)(2) adopts ICD-10-CM, including the Official Guidelines for Coding and Reporting, for diseases, injuries, impairments, other health problems and their manifestations, and causes of injury, for the period on and after October 1, 2015. CMS puts the reach plainly on its ICD-10 page: ICD-10 applies to all parties covered by HIPAA, not just providers who bill Medicare or Medicaid. The guidelines themselves, approved by the four Cooperating Parties (the American Hospital Association, AHIMA, CMS and NCHS), say adherence to them is required under HIPAA.

The set is rebuilt once a fiscal year and takes effect October 1. The FY 2026 files, dated June 6, 2025, carry 74,719 codes and are the set in force for encounters from October 1, 2025 through September 30, 2026; against FY 2025 they added 487 codes, deleted 28 and revised 38. CMS also posts an April 1 refresh each year, because a mid-year update is possible: 42 codes for health-related social needs went in on April 1, 2023. The April 1, 2026 file records no additions, no deletions and no revisions, so the October 2025 set stands. FY 2027, effective October 1, 2026, holds 74,879 codes after 190 additions, 30 deletions and 4 revisions.

Where the dental codes sit is the part worth memorizing. Chapter 11, diseases of the digestive system (K00-K95), opens with the block for diseases of oral cavity and salivary glands, K00 through K14, which in FY 2026 holds 202 entries across thirteen three-character categories: K00 disorders of tooth development and eruption, K01 embedded and impacted teeth, K02 dental caries, K03 other diseases of hard tissues of teeth, K04 diseases of pulp and periapical tissues, K05 gingivitis and periodontal diseases, K06 other disorders of gingiva and edentulous alveolar ridge, K08 other disorders of teeth and supporting structures, K09 cysts of oral region, K11 diseases of salivary glands, K12 stomatitis and related lesions, K13 other diseases of lip and oral mucosa, and K14 diseases of tongue. K07 and K10 are not there; their content is in M26 and M27.

The rest of a dentist's working list lives outside that block. M26, dentofacial anomalies including malocclusion, holds 78 codes, from Angle's classes at M26.211 through M26.213 to the temporomandibular joint disorders grouped under M26.6. M27, other diseases of jaws, including M27.51 through M27.59 for periradicular pathology after endodontic treatment and M27.61 through M27.69 for dental implant failures. A traumatic tooth fracture is S02.5 with a seventh character for the encounter, such as S02.5XXA for the initial encounter. A dental examination is Z01.20 without abnormal findings or Z01.21 with them. Caries carries its own structure, for example the smooth-surface trio K02.61, K02.62 and K02.63 for enamel, dentin and pulp. Periodontitis is staged in the code itself: K05.311 through K05.319 for localized chronic periodontitis by severity, and the K05.32 series for generalized.

Who it applies to#

Every practice that sends a claim carrying a diagnosis. The ADA's completion instructions are the operative rule for the paper and electronic dental claim: item 34 is the diagnosis code list qualifier, where AB means ICD-10-CM, and item 34a takes up to four codes lettered A through D with the primary one adjacent to A. The instructions make both items required when the diagnosis may have an impact on adjudication of a claim where specific dental procedures may minimize risks tied to the connection between oral and systemic health, or when state regulation such as Medicaid or a third-party payer contract requires it.

Everything sent to a medical plan is a different matter. The ADA states that ICD-10-CM is the only diagnosis code set that may be used on claims to dental benefit plans, and that on claims for dental services submitted to medical plans diagnosis codes are always required. That is the case for medically necessary oral surgery, sleep appliances, trauma and the inextricably linked services Medicare pays for.

What changed#

Nothing structural this year for dentistry. The FY 2026 addendum's 487 additions and 28 deletions touched no code in K00 through K14 or in M26 and M27, and neither does the FY 2027 addendum. The dental families have been stable since the 2015 transition; what moves is the rest of the classification around them.

The practical change is administrative. Because the April 1, 2026 update carried zero changes, a practice on the October 2025 file is current through September 30, 2026, and the next date to act on is October 1, 2026, when FY 2027 replaces it. A claim must use the version valid for the date of service, and NCHS's free browser tool lets you search in a particular fiscal year to confirm which code was live on a given day.

Where the source is#

The NCHS ICD-10-CM page at cdc.gov is the classification's home and links the free browser tool, the tabular list and the index. CMS posts each fiscal year's complete files, including the code descriptions in tabular order, the addendum and the Official Guidelines, on its ICD-10 page; the counts in this entry were taken from the FY 2026 and FY 2027 code description files themselves. The legal adoption is 45 CFR 162.1002 on eCFR. The claim-form rules are in the ADA Dental Claim Form completion instructions, version 2024, a free PDF on ada.org, and the ADA's own coding FAQ carries its statement about which code sets may appear on a dental claim. Note that cdc.gov refused automated requests sent with a browser user agent from this environment and answered a plain one; the pages were read successfully that way.