2026 ICD-10-CM Diagnosis Code K05.321Chronic periodontitis, generalized, slight

ICD-10-CM Codes›K00–K95›K00-K14›K05

ICD-10-CM K05.321
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K05.321 is a billable ICD-10-CM diagnosis code for chronic periodontitis, generalized, slight. 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 AAP/EFP 2017 Classification of Periodontal and Peri‐implant Diseases and Conditions generalized periodontitis Stage 1 Grade A. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Any dental condition including traumatic injury; Caries, periodontitis, and other preventable dental conditions; and Disorders of teeth and gingiva.

Code Identity

ICD-10-CM Code
K05.321
Billable Status
Yes — Valid for Submission
Code Describes
Chronic periodontitis, generalized, slight
Short Description
Chronic periodontitis, generalized, slight
Same as the full description in the CMS dataset.
Parent Code
K05.32
Chronic periodontitis, generalized

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK00-K14Diseases of oral cavity and salivary glands
CategoryK05Gingivitis and periodontal diseases
This CodeK05.321Chronic periodontitis, generalized, slight

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • AAP/EFP 2017 Classification of Periodontal and Peri‐implant Diseases and Conditions generalized periodontitis Stage 1 Grade A
  • AAP/EFP 2017 Classification of Periodontal and Peri‐implant Diseases and Conditions generalized periodontitis Stage 1 Grade B
  • AAP/EFP 2017 Classification of Periodontal and Peri‐implant Diseases and Conditions generalized periodontitis Stage 1 Grade C
  • Generalized chronic periodontitis
  • Generalized slight chronic periodontitis

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.

    • Periodontitis(chronic) (complex) (compound) (local) (simplex)
      • generalized
        • slight

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 DEN003
Caries, periodontitis, and other preventable dental conditions
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

Patient EducationClinical

Gum Disease

If you have gum disease, you're not alone. Many U.S. adults currently have some form of the disease. It ranges from simple gum inflammation, called gingivitis, to serious damage to the tissue and bone supporting the teeth. In the worst cases, you can lose teeth.

Read the full article at MedlinePlus

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

Convert K05.321 to ICD-9-CMHistory

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

ICD-9-CM
523.42 Chron periodontitis,gen
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement K05.321 replaces the following previously assigned code(s):

  • K05.32 - Chronic periodontitis, generalized
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K05.321Overview

Is K05.321 (Chronic periodontitis, generalized) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report chronic periodontitis, generalized, slight on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K05.321 group to?

When chronic periodontitis, generalized, slight 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 K05.321?

Under the General Equivalence Mappings, chronic periodontitis, generalized, slight converts to ICD-9-CM 523.42 (chron periodontitis,gen). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.