Posterior composites are among the most common procedures in restorative dentistry today. Patients prefer tooth-colored fillings, and most dentists have moved away from amalgam. But even as composite fillings have become standard, billing them correctly—and getting paid fairly—still trips up many dental teams.

The result? Unintentional write-offs and thousands in lost revenue each year.

Let’s break down D2391 through D2394, when to use them, and how to protect your practice from doing free dentistry.

The Posterior Composite Codes – What They Mean

CDT CodeDescriptionD2391Resin-based composite – one surface, posteriorD2392Resin-based composite – two surfaces, posteriorD2393Resin-based composite – three surfaces, posteriorD2394Resin-based composite – four or more surfaces, posterior

These codes apply to tooth-colored fillings on posterior teeth (molars and premolars) and should be used based on the number of surfaces restored.

Important: Always code based on the actual number of surfaces restored, not the size of the cavity or how long the procedure took.

Common Trap: The Composite Downgrade to Amalgam

Many dental insurance plans downgrade posterior composites to the reimbursement amount for amalgam restorations. This is known as an "alternate benefit" clause.

Here’s where the trap happens:
Some offices mistakenly write off the difference between the composite fee and the amalgam allowance—even when they’re not contractually obligated to do so.

The Right Way to Handle It:

• Always bill the procedure you performed — if you placed a composite, use the appropriate D2391–D2394 code.

• If the insurance plan downgrades to amalgam, and you’re out-of-network or the patient has a non-covered benefit, you can bill the patient the difference (as long as you’ve disclosed it upfront).

• Even if you’re in-network, check your contract—not all PPO agreements require you to write off the downgraded amount.

Patient Script Example:
“Your plan only pays for silver fillings on back teeth, but we’re doing a tooth-colored restoration for a more natural look. The plan will pay the equivalent of a silver filling, and you’ll be responsible for the difference. We’ll review the estimate before we start.”

Code Selection Tips: Don’t Undercode

Dentists sometimes undercode composite restorations out of habit or fear of claim denial. For example:

• Billing D2392 (two surfaces) when three surfaces were actually restored.

• Avoiding D2394 (four or more surfaces) because it has a higher fee and may be flagged by insurance.

But this only hurts your practice. Undercoding = underpayment, and you’re doing more work for less money.

Always document:

• Tooth number,

• Surfaces restored (e.g., MO, MODL),

• Why the restoration was necessary (e.g., decay, fracture, defective filling),

• Radiographic or clinical evidence if needed (especially for multi-surface restorations).

Coordination Between Clinical and Front Office

Ensure your clinical team is accurately charting surfaces, and your admin team is coding accordingly. Miscommunication here is a major cause of lost revenue.

Pro Tip: Review a few claims each month as a team. Compare what was charted vs. what was billed. You'll be surprised how often surfaces are under-recorded—and underbilled.

Don’t Let Fear of Denial Lead to Free Dentistry

Yes, insurance may push back—especially on D2393 or D2394. But as long as your documentation supports the procedure, you should submit the correct code every time.

• Don’t let fear of denials force you into billing D2392 when it was really a D2394.

• Don't default to the amalgam code just because you know it will be paid.

• Don’t write off differences without checking your rights first.

Final Thoughts: Bill What You Do, Get Paid What You Deserve

Posterior composites are often undervalued—not because the work isn’t important, but because coding and billing mistakes lead to lost income. By mastering D2391–D2394, you can:

• Improve insurance reimbursement,

• Reduce write-offs,

• Protect your production value, and

• Make sure every restoration you perform is recognized and paid appropriately.