2026 ICD-10-CM Diagnosis Code K04.6Periapical abscess with sinus

ICD-10-CM Codes›K00–K95›K00-K14›K04

ICD-10-CM K04.6
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K04.6 is a billable ICD-10-CM diagnosis code for periapical abscess with sinus. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 157 through 159. Coders also document this condition as oral fistula. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Any dental condition including traumatic injury, Disorders of teeth and gingiva, and Nontraumatic dental conditions.

Code Identity

ICD-10-CM Code
K04.6
Billable Status
Yes — Valid for Submission
Code Describes
Periapical abscess with sinus
Short Description
Periapical abscess with sinus
Same as the full description in the CMS dataset.
Parent Code
K04
Diseases of pulp and periapical tissues

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK00-K14Diseases of oral cavity and salivary glands
CategoryK04Diseases of pulp and periapical tissues
This CodeK04.6Periapical abscess with sinus

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Oral fistula
  • Periapical abscess
  • Periapical abscess with facial involvement
  • Periapical abscess with sinus tract

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Dental abscess with sinus
  • Dentoalveolar abscess with sinus

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • alveolar
        • with sinus
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • apical (tooth)
        • with sinus (alveolar)
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • dental
        • with sinus (alveolar)
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • dentoalveolar
        • with sinus
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • lateral (alveolar)
        • with sinus
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • maxilla, maxillary
        • molar (tooth)
          • with sinus
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • periapical
        • with sinus (alveolar)
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • root, tooth
        • with sinus (alveolar)
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • septal, dental
        • with sinus (alveolar)
    • Abscess(connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
      • tooth, teeth (root)
        • with sinus (alveolar)
    • Fistula(cutaneous)
      • alveolar process
    • Fistula(cutaneous)
      • dental
    • Fistula(cutaneous)
      • from periapical abscess
    • Gumboil
      • with sinus
    • Parulis
      • with sinus
    • Sinus
      • dental

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR DEN001
Any dental condition including traumatic injury
Default principal diagnosis: inpatient No · outpatient No
CCSR DIG002
Disorders of teeth and gingiva
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR DEN002
Nontraumatic dental conditions
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Periapical Abscess

    acute or chronic inflammation of tissues surrounding the apical portion of a tooth, associated with the collection of pus, resulting from infection following pulp infection through a carious lesion or as a result of an injury causing pulp necrosis. (dorland, 27th ed)

  • Oral Fistula

    an abnormal passage within the mouth communicating between two or more anatomical structures.

  • Periapical Abscess with Sinus

    localized collection of pus in the tissues that enclose the root of a tooth and is associated with the presence of a sinus tract.

Patient EducationClinical

Abscess

An abscess is a pocket of pus. You can get an abscess almost anywhere in your body. When an area of your body becomes infected, your body's immune system tries to fight the infection. White blood cells go to the infected area, collect within the damaged tissue, and cause inflammation. During this process, pus forms.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert K04.6 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
522.7 Periapical absc w sinus
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K04.6Overview

Is K04.6 (Diseases of pulp and periapical tissues) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report periapical abscess with sinus on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K04.6 group to?

When periapical abscess with sinus is the principal diagnosis on an inpatient stay, it groups to MS-DRG 157, 158, 159, with relative weights from 0.7085 to 1.7168 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K04.6?

Under the General Equivalence Mappings, periapical abscess with sinus converts to ICD-9-CM 522.7 (periapical absc w sinus). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.