Reviewed by Morgan Heminger · Updated September 23, 2026

What Is D2391? (CDT Code Overview)

CDT code D2391 is the dental procedure code for a one-surface resin-based composite restoration on a posterior tooth: the tooth-colored filling on a premolar or molar that covers a single surface. It belongs to the Restorative category of CDT codes (Resin-Based Composite Restorations, Direct subcategory). It is the posterior composite dental code for one surface; two surfaces is D2392, and a one-surface composite on a front tooth is D2330.

When Should You Use D2391?

The D2391 dental code applies to resin-based composite restorations covering one surface of a back tooth. This code should be used when a dentist fills a single surface (occlusal, buccal, or lingual) of a premolar or molar with tooth-colored composite material. It's essential to differentiate D2391 from related composite codes like D2392 (two surfaces) or D2393 (three surfaces), to maintain proper billing practices and prevent claim rejections. Apply D2391 only when the filling involves one surface and doesn't cross over to facial or lingual surfaces past the line angles.

Quick reference: Use D2391 when the clinical scenario specifically matches resin-based composite restorations. Do not use this code as a substitute for related procedures in the same category. Consider whether D2330 (Anterior Composite Restorations) or D2331 (Anterior Composite Restoration) might be more appropriate instead.

D2391 vs. Similar CDT Codes: Key Differences

Dental teams frequently confuse D2391 with other codes in the resin-based composite restorations range. Here is how D2391 differs from the most commonly mixed-up codes:

Documentation Requirements for D2391

Accurate documentation plays a vital role in securing proper reimbursement. Clinical records must clearly indicate the tooth number, the exact surface treated, and the treatment rationale (such as decay, fracture, or replacing a damaged filling). When available, include before and after radiographs or clinical photographs to support the procedure's necessity. For instance, a clinical entry might read: "Tooth #30, occlusal surface, decay removed and restored with resin composite. Pre-treatment radiograph included." This thorough approach helps validate the D2391 code usage and speeds up insurance claim processing.

Documentation checklist for D2391:

• Patient chief complaint and relevant medical/dental history clearly recorded.

• Clinical findings that support the use of D2391 specifically (not a more general or more specific code).

• Any diagnostic tests, imaging, or supplementary data that justify the procedure.

• Treatment plan with rationale connecting the diagnosis to the procedure coded as D2391.

• Post-procedure notes, including outcomes and follow-up recommendations.

For a deeper look at documentation best practices, see our guide on How Clinical Documentation Quality Drives Dental Claim Approvals.

Insurance and Billing Guide for D2391

To improve payment success and reduce claim denials for D2391, consider these guidelines:

• Check patient coverage prior to treatment to ensure posterior composite benefits are available, since some insurance plans may reimburse at amalgam rates.

• File comprehensive claims including thorough clinical documentation and supporting visuals.

• Select proper CDT codes—avoid incorrect coding based on surface numbers.

• When claims face denial or downgrades, submit appeals with supporting evidence, highlighting why composite material was clinically preferred over amalgam.

• Track outstanding receivables and follow up quickly on delayed payments to ensure steady cash flow.

Being thorough with benefit verification and record-keeping minimizes administrative challenges and promotes faster payment processing.

Common denial reasons for D2391: Lack of clinical documentation, frequency limitations exceeded, code mismatch with diagnosis, or missing prior authorization. When appealing a denied D2391 claim, include a detailed narrative explaining why the procedure was necessary, supporting clinical evidence, and relevant imaging or test results. Many practices find that well-documented first submissions dramatically reduce the need for appeals.

What major payers publish about D2391:

• Delta Dental of Virginia covers resin on back teeth only on the buccal surfaces of premolars under its model policy. Elsewhere it pays an alternate benefit up to the amalgam fee, and the patient pays the difference. Replacing a filling within 24 months is not billable when done by the same office (Delta Dental of Virginia Participating Dentists' Handbook, 2026).

• Delta Dental of Virginia notes that D1352 (preventive resin restoration) was deleted in CDT 2026 and that D2391 is used in its place (Delta Dental of Virginia Participating Dentists' Handbook, 2026).

• Cigna allows D2391 when records confirm decay or breakdown that needs a filling, but not for cosmetic reasons, for wear or erosion without symptoms, or when the same office replaces the same tooth and surface within 12 months (Cigna Dental Coverage Determination Guidelines, 2026).

• UnitedHealthcare asks for a narrative of necessity if the tooth already has a crown, and does not consider composites indicated for patients with heavy bruxism, extensive active decay or high caries risk (UnitedHealthcare Dental Claim Review Guidelines, January 2026; UnitedHealthcare Single Tooth Direct Restorations policy DCP023.15, May 2026).

These are the payers' published policy documents; the patient's own plan can set different frequencies and alternate benefits, so confirm them during insurance verification.

To improve your overall claims workflow, explore How to Write Narratives for Dental Claims? 7 Tips.

Real-World Case Example: Billing D2391

A patient presents requiring a procedure consistent with D2391 (resin-based composite restorations). The treating dentist documents the clinical findings, performs the procedure as indicated, and records detailed notes including the diagnosis, technique, and outcome. The billing team verifies insurance coverage, submits the claim with D2391 and supporting documentation, and follows up to ensure timely reimbursement. When the initial claim is processed, the practice reviews the Explanation of Benefits and addresses any discrepancies promptly.

Related CDT Codes to D2391

If you are researching D2391, you may also need to reference these related CDT codes in the resin-based composite restorations range and beyond:

• D1351: Sealant Application — Learn when to use D1351 and how it differs from D2391.

• D1354: Interim Caries Arresting Medicament Application — Learn when to use D1354 and how it differs from D2391.

• D2140: Amalgam Restoration Guide — Learn when to use D2140 and how it differs from D2391.

• D2150: Two-Surface Amalgam Restoration — Learn when to use D2150 and how it differs from D2391.

• D2330: Anterior Composite Restorations — Learn when to use D2330 and how it differs from D2391.

Frequently Asked Questions About D2391

Is it appropriate to bill D2391 alongside other restorative procedures on the same tooth?

D2391 cannot be billed with other restorative codes for the same surface of the same tooth during a single visit. When restoring multiple surfaces on one posterior tooth, the correct approach is to use the appropriate multi-surface composite codes (D2392, D2393, or D2394) rather than submitting multiple single-surface codes. Proper coding must accurately represent the actual clinical work performed. Always verify with the specific insurance carrier, as policies and coverage rules can vary significantly between payers. Maintaining thorough documentation for D2391 will strengthen your position in any audit or appeal scenario.

Does D2391 have any age-related restrictions for younger patients?

D2391 has no inherent age limitations and is appropriate for both children and adults when the clinical situation matches the code description. However, individual insurance carriers may impose specific coverage policies or frequency restrictions for pediatric composite restorations, making it essential to confirm patient benefits and payer requirements prior to beginning treatment. Always verify with the specific insurance carrier, as policies and coverage rules can vary significantly between payers. Maintaining thorough documentation for D2391 will strengthen your position in any audit or appeal scenario.

What steps should be taken when a properly documented D2391 claim gets denied?

When facing a D2391 claim denial with seemingly adequate documentation, first examine the Explanation of Benefits to identify the specific denial reason. Frequent causes include benefit downgrades to amalgam coverage or insufficient supporting documentation. For questionable denials, submit a formal appeal accompanied by comprehensive supporting materials including detailed treatment narratives, diagnostic radiographs, and clinical photographs. Maintain detailed records of all communications and directly contact the insurance carrier for clarification when necessary.

What is the typical reimbursement range for D2391?

2026 Medicaid fee schedules give a public reference point for D2391: Medi-Cal Dental allows up to $39.00 (Medi-Cal Dental Schedule of Maximum Allowances, July 2026), New York Medicaid pays $50.50 (New York Medicaid dental fee schedule, January 2026), Florida Medicaid pays $46.28 for patients under 21 (Florida AHCA Dental Fee Schedule, January 2026) and Texas Medicaid pays $85.19 for patients under 21 (Texas Medicaid (TMHP) THSteps dental fee schedule). Commercial PPO reimbursement depends on the payer contract, your region and network status, so the most reliable number for your practice is the allowed amount on your recent EOBs for D2391.

Does D2391 require prior authorization?

Prior authorization requirements for D2391 depend on the patient's specific insurance plan. Some carriers require advance approval for procedures coded under D2391, while others process claims without it. Best practice is to verify authorization requirements during insurance eligibility checks before the appointment. If prior authorization is required, submit the request with detailed clinical notes and supporting documentation to avoid delays in patient care and claim processing.