2026 ICD-10-CM Diagnosis Code K08.421Partial loss of teeth due to periodontal diseases, class I

ICD-10-CM Codes›K00–K95›K00-K14›K08

ICD-10-CM K08.421
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K08.421 is a billable ICD-10-CM diagnosis code for partial loss of teeth due to periodontal diseases, class I. 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 partial edentulism class 1. 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
K08.421
Billable Status
Yes — Valid for Submission
Code Describes
Partial loss of teeth due to periodontal diseases, class I
Short Description
Partial loss of teeth due to periodontal diseases, class I
Same as the full description in the CMS dataset.
Parent Code
K08.42
Partial loss of teeth due to periodontal diseases

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK00-K14Diseases of oral cavity and salivary glands
CategoryK08Other disorders of teeth and supporting structures
This CodeK08.421Partial loss of teeth due to periodontal diseases, class I

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Partial edentulism class 1
  • Partial edentulism class I due to periodontal disease
  • Partial edentulism due to periodontal disease

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.

    • Absence(of) (organ or part) (complete or partial)
      • teeth, tooth (congenital)
        • acquired (complete)
          • partial
            • due to
              • periodontal disease
                • class I

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 K08.421 to ICD-9-CMHistory

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

ICD-9-CM
525.51 Part edentulism,class I
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
525.12 Loss teeth d/t peri dis
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

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 K08.421Overview

Is K08.421 (Partial loss of teeth due to periodontal diseases) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report partial loss of teeth due to periodontal diseases, class I on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K08.421 group to?

When partial loss of teeth due to periodontal diseases, class I 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 K08.421?

Under the General Equivalence Mappings, partial loss of teeth due to periodontal diseases, class I converts to ICD-9-CM 525.51 (part edentulism,class I) and 525.12 (loss teeth d/t peri dis). 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.