D2391 Dental Code: One-Surface Posterior Composite

The short version

# D2391 Dental Code: One-Surface Posterior Composite

D2391 is the CDT code for a resin-based composite restoration involving one surface of a posterior tooth. Starting with CDT 2026, the code is no longer limited by how deeply the lesion extends, so the surface count and material now control the selection. A wrong surface entry can reduce the benefit or create an audit problem.

Bill D2391 for one resin-composite restoration on one named surface of a premolar or molar.
CDT 2026 removed the old lesion-depth restriction. D2391 can now report the one-surface posterior composite regardless of lesion depth or diagnosis.
Use D2392 when the finished restoration involves two surfaces. Use D2140 when the one-surface posterior material is amalgam.
A 2026 Delta Dental Texas plan lists a $65 adult copayment for D2391, excludes it as a pediatric benefit, and lists a $25 copayment for D2140.
In a worked PPO example, a $225 fee becomes a $175 allowable. The plan pays $140 at 80%, the patient owes $35, and the office adjusts $50.
Record the tooth, exact surface, diagnosis, material, and final extent. Preserve an image when it helps show why the reported surface count is correct.

What is D2391?

D2391 reports a direct tooth-colored restoration on one surface of a posterior tooth. Posterior means a premolar or molar. The code follows the completed restoration's surface count, not the number of separate carious spots or the depth of the lesion.

Fact	D2391
CDT category	Restorative
Unit	Per tooth
Material	Resin-based composite
Tooth area	Posterior
Surface count	One
2026 change	Prior lesion-depth restriction deleted effective January 1, 2026
Public fee examples	Washington Medicaid listed $59.97 for adults; South Carolina listed $117 for children in 2025 schedules

The ADA's 2026 revision article says the deletion lets dentists report D2391 regardless of lesion depth or diagnosis.

When do you bill D2391?

Bill D2391 when the dentist places one posterior composite restoration and the finished restoration occupies one reportable tooth surface.

Identify the treated premolar or molar.
Name the restored surface, such as occlusal, buccal, lingual, mesial, or distal.
Confirm that the preparation and final restoration don't extend onto a second surface.
Record resin composite as the material placed.
Use the current CDT 2026 rule without an unsupported dentin-depth test.

The clinical diagnosis still belongs in the chart. It just no longer changes whether a one-surface posterior composite fits D2391.

D2391 vs D2392 and D2140

Count the restored surfaces first, then confirm the material.

Posterior composite codes rise with the number of restored surfaces, while a one-surface amalgam uses D2140 instead.

	D2140	D2391	D2392
Material	Amalgam	Resin composite	Resin composite
Tooth	Primary or permanent posterior tooth	Posterior tooth	Posterior tooth
Surfaces	One	One	Two
Washington adult Medicaid fee	Check current schedule	$59.97	$72.24

The surface isn't counted twice because the restoration has separate extensions on the same named surface. It becomes D2392 when the preparation or restoration crosses onto a second reportable surface. The chart and claim should use the same abbreviations so a reviewer doesn't have to infer the count.

The ADA's 2025 downcoding report describes a payer reducing a documented two-surface composite to a single-surface benefit.

What does insurance actually do with D2391?

Plan treatment of posterior resin can change by age and product. A published 2026 Delta Dental Texas plan lists D2391 as no pediatric benefit and a $65 adult copayment, while D2140 has a $25 copayment for both. A Delta California pediatric schedule instead lists D2391 with a $30 copayment and limits posterior restorations by provider and tooth history. Verify the actual plan before discussing the balance.

A $225 D2391 charge becomes a $175 allowable, with $140 from the plan, $35 from the patient, and a $50 adjustment.

Office fee: $225
Contracted allowable: $175
Contractual adjustment: $50
Plan payment at 80%: $140
Patient coinsurance: $35

Why does D2391 get denied?

The history doesn't clear the plan's replacement interval for that tooth and surface.
The note and claim don't agree on one restored surface.
The plan doesn't cover posterior composite for the patient's age or pays another material benefit.
The office hasn't removed its pre-2026 lesion-depth rule.
The claim doesn't identify the tooth, surface, or material.

Don't post a changed procedure before comparing the EOB, submitted surface, and plan language.

What documentation gets D2391 paid?

Record the tooth number and the single restored surface.
State the diagnosis or reason for replacement.
Identify the resin-composite material and any relevant shade or isolation detail used by the office.
Describe recurrent decay, fracture, or failed restoration when replacement history may be reviewed.
Keep a preoperative image when it supports the lesion or existing restoration.
Confirm the completed restoration didn't extend to a second reportable surface.

Common questions about D2391

Does D2391 still require the lesion to enter dentin?

No, it doesn't. The ADA removed that restriction for CDT 2026. D2391 now reports a one-surface posterior composite regardless of lesion depth or diagnosis. The dentist still documents the diagnosis and clinical need, but depth no longer decides the code. Use the current code and keep the preoperative findings in the record.

What happened to D1352 in 2026?

D1352 was deleted when the D2391 restriction was removed. The ADA said the procedures could be documented with the updated D2391, which reduced confusion. Update favorites, templates, and claim rules so the deleted code doesn't continue to leave the office.

Can a payer pay D2140 when the office reports D2391?

A plan can limit its posterior resin benefit or use a lower material benefit, but the office should still report the composite that was placed. Check the contract and EOB to determine whether the difference is billable to the patient. Don't change the clinical record to amalgam when no amalgam was used.

How do you decide between D2391 and D2392?

Count the named surfaces occupied by the completed restoration. One surface is D2391 and two are D2392. When the restoration crosses a line angle onto another surface, document both surfaces clearly. Photos or radiographs can support a disputed count, but the operative note should stand on its own.

Update the old D2391 rule

Before filing D2391, confirm the tooth, one restored surface, material, and EOB explanation.

Sources

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