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K08.51 vs M27.5

K08.51 (Open restoration margins of tooth) compared with M27.5 (Periradicular pathology associated with previous endodontic treatment), from the official CMS tabular data.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Summary

These codes can be reported together when both conditions are documented, because K08.51 lists M27.5 under Excludes2, which marks them as distinct conditions.

Official rule
What is different?

The conditions named, billing status and chapter.K08.51 is “Open restoration margins of tooth”; M27.5 is “Periradicular pathology associated with previous endodontic treatment”. M27.5 is a non-billable header; K08.51 is billable. K08.51 sits in K00-K95 — Diseases of the Digestive System (K00-K95); M27.5 in M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99).

Registry fact

Can these codes be reported together?

Yes, when both are documented.K08.51 lists M27.5 under Excludes2: “unsatisfactory endodontic treatment (M27.5-)”. Excludes2 marks distinct conditions that may both be reported when both are documented.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code. K08.51 carries 1 Excludes1 note and M27.5 carries 2 Excludes1 notes covering other codes; the side-by-side table quotes them.

Official rule

Is there an Excludes2 relationship?

Yes.K08.51’s tabular entry: “unsatisfactory endodontic treatment (M27.5-)”. The note covers M27.5.

Official ruleGuide: Excludes1 vs Excludes2

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

One is a header.M27.5 is a non-billable header, but K08.51 is not one of its subdivisions.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Informational

Excludes2 relationship

K08.51
Open restoration margins of tooth
↔
M27.5
Periradicular pathology associated with previous endodontic treatment

What we found

Yes, when both are documented.K08.51 carries an Excludes2 note covering M27.5: “unsatisfactory endodontic treatment (M27.5-)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.A.12.b — Excludes2 · applies to: Excludes2

    A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

    ICD-10-CM Official Guidelines FY2027

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.

Official descriptionDiffers
K08.51

Open restoration margins of tooth

M27.5

Periradicular pathology associated with previous endodontic treatment

StatusDiffers
K08.51
Billable
M27.5
Non-billable header

A header is not reported on a claim; a code beneath it is.

Report instead: M27.51, M27.52, M27.53, M27.59

Excludes1Differs
K08.51
  • dental restoration status (Z98.811)
M27.5
  • hemifacial atrophy or hypertrophy (Q67.4)
  • unilateral condylar hyperplasia or hypoplasia (M27.8)
Excludes2Differs
K08.51
  • endosseous dental implant failure (M27.6-)
  • unsatisfactory endodontic treatment (M27.5-)
  • dentofacial anomalies [including malocclusion] (M26.-)
  • disorders of jaw (M27.-)
M27.5

None at this code

CategoryDiffers
K08.51

K08 Other disorders of teeth and supporting structures

M27.5

M27 Other diseases of jaws

ChapterDiffers
K08.51

K00-K95 — Diseases of the Digestive System (K00-K95)

M27.5

M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99)

IncludesDiffers
K08.51
  • Dental restoration failure of marginal integrity
  • Open margin on tooth restoration
  • Poor gingival margin to tooth restoration
M27.5

None at this code

No Code first, Use additional code, Code also and 7th character note at either code.

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on. In a row that differs, notes every code shares are dimmed.

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Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources