M26.29 captures dental arch relationship anomalies that don't fit any more specific subcategory under M26.2 — including midline deviation of the dental arch, excessive deep/horizontal/vertical overbite, and posterior lingual occlusion of mandibular teeth.

Documentation tips

What should appear in the chart to support M26.29.

Source · Editorial brief grounded in 6 cited references ↓

• Specify the exact arch anomaly type — midline deviation, deep overbite, horizontal overbite, vertical overbite, or posterior lingual occlusion — so auditors can confirm that a more specific M26.2x code does not apply.
• Document imaging findings (cephalometric radiographs, panoramic X-rays, CBCT) that confirm the arch relationship finding, including measurement values where available (e.g., overbite depth in mm).
• Record the clinical presentation and any functional impairment (chewing difficulty, speech impact, TMJ symptoms) to support medical necessity when the diagnosis is linked to a surgical or orthodontic treatment plan.
• If midline deviation is documented, note whether it is skeletal or dental in origin — this distinction may be needed for surgical planning and can affect payer medical necessity criteria.
• When overbite is the basis for M26.29, confirm it is 'excessive' per clinical documentation; routine overbite within normal limits does not support this code.

Related CPT procedures

Procedure codes commonly billed with M26.29. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

Common coding pitfalls

The recurring mistakes coders make with M26.29 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

• Defaulting to M26.29 without first ruling out a more specific sibling: excessive horizontal overlap maps to M26.23, reverse articulation to M26.24, and interarch distance anomalies to M26.25 — using M26.29 when a specific code exists is a specificity error.
• Confusing M26.29 (arch relationship anomaly) with M26.39 (anomalies of tooth position of fully erupted teeth) — crowding, spacing, or individual tooth displacement belongs under M26.3x, not M26.29.
• Assigning M26.29 for a generalized malocclusion without identifying the arch relationship component; unspecified malocclusion codes to M26.4, not M26.29.
• Omitting this code when overbite or midline deviation is a secondary driver of a jaw surgery — M26.29 should be listed alongside the primary surgical indication code when the arch anomaly independently influences the procedure.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

Inclusion & exclusion notes

Per the official ICD-10-CM Tabular List.

Source · CDC ICD-10-CM Official Tabular List · 2026

Sibling codes

Other billable codes under M26.2 (laterality / anatomic variants).