D2391 is the CDT code for a one-surface resin-based composite (tooth-colored) filling on a posterior (back) tooth — a single-surface restoration on a premolar or molar using tooth-colored material. It is reported per restoration, chosen by surface count and tooth location.
Informational only — confirm the official CDT descriptor and your payers' rules independently. This is general guidance, not billing, coding, or clinical advice.
When to Use the D2391 Code
Report D2391 when a back tooth (premolar or molar) is restored with resin-based composite material on a single surface — for example, a small occlusal cavity or chip on a posterior tooth. Posterior composite codes run by surface count: D2391 is one surface, with two-, three-, and four-plus-surface posterior composites carrying their own higher numbers.
Don't confuse D2391 with the anterior composite series, such as D2330 for a one-surface front-tooth composite — location matters. And don't mix it up with the amalgam codes (D2140 and up), which use silver material on the same teeth. Code by both the material placed and the tooth's position in the arch.
Documentation & Clinical Scenarios
A one-surface back-tooth composite is routine, but the record should still show what was treated and why:
- Tooth number confirming it's a posterior tooth, and the specific surface restored.
- The diagnosis — caries, fracture, chip, or a failing prior restoration — justifying the filling.
- The material (resin-based composite) and that one surface was involved.
- Supporting evidence such as a bitewing radiograph when decay isn't clinically obvious.
Note that the 2026 descriptor revision removed older language tying this code to dentin penetration; report a one-surface posterior composite by surface and location. If more than one surface is restored, code up to the appropriate posterior composite rather than reporting multiple D2391 lines.
Insurance & Billing Tips
- Verify the restorative benefit. Most plans cover composites as a basic service at a coinsurance level after any deductible.
- Watch for amalgam down-coding. Many plans reimburse a posterior composite at the rate of the equivalent amalgam filling (D2140), leaving the patient responsible for the difference. Confirm the plan's policy and set expectations.
- Surface count drives the fee. One surface reimburses differently than two or three, so report exactly what was placed.
- Check replacement frequency. Plans commonly limit re-restoration of the same tooth/surface (e.g., once every 24 months).
- Document the surface clearly so the one-surface posterior restoration adjudicates correctly.
Example Case
A patient comes in for a small cavity on the chewing surface of a lower molar and wants a tooth-colored filling. The dentist removes the decay and places a one-surface composite. The visit is coded D2391 for the posterior tooth, single surface, with a bitewing on file. Because the office verified the benefit and warned the patient the plan may pay at the amalgam rate, the explanation of benefits matches expectations and there's no billing surprise.
Patients call about "a white filling on my back tooth" — not D2391. DentalReception AI answers and books those calls 24/7, captures insurance details for clean intake, and routes clinical and billing questions to your team. See how it handles filling calls, or book a demo.
Frequently Asked Questions
What's the difference between D2391 and D2330?
Tooth location. D2391 is a one-surface composite on a posterior (back) tooth, while D2330 is a one-surface composite on an anterior (front) tooth. Both are tooth-colored and single-surface, but front and back composites are coded separately and are often reimbursed differently, so code by the tooth's position in the arch.
Will insurance pay the full composite rate on a back tooth?
Not always. Many plans apply an alternate benefit and reimburse a posterior composite at the rate of the equivalent amalgam filling (D2140), leaving the patient to cover the difference. Verifying benefits before treatment lets you tell the patient up front whether the plan down-codes to amalgam, so the estimate is accurate.
Is D2391 a silver filling or a tooth-colored filling?
D2391 is a tooth-colored, resin-based composite filling on a back tooth. The silver (amalgam) equivalent for one posterior surface is D2140. Code by the material actually placed, because the choice affects both the code and, frequently, how the plan reimburses the restoration.
Do I need a pre-authorization for a D2391 filling?
Routine single-surface posterior fillings usually don't require pre-authorization, but because of common amalgam down-coding it's worth verifying the benefit and the plan's composite policy beforehand. That lets you quote an accurate out-of-pocket amount. Keep the tooth number, surface, and any radiograph documented in case of a post-payment review.
Confirm the current CDT descriptor and your specific payer policies before billing — browse the full dental code library or see our insurance verification feature.