D2791 Dental Code: Full Cast Base Metal Crown Billing

What D2791 covers

D2791 reports a full-cast crown made entirely of predominantly base-metal alloy. Full cast means all metal, with no porcelain or ceramic on any surface. Predominantly base metal means the casting contains less than 25% noble metal by weight, the bottom tier of the ADA’s casting-alloy classification. Nickel-chromium and cobalt-chromium are the common alloys. The code covers the prep, impression, lab fabrication, try-in, and cementation, and applies to permanent teeth.

It does not cover:

• A full-cast crown made of high noble alloy. That’s D2790.
• A full-cast crown made of noble alloy. That’s D2792.
• A full-cast crown made of titanium or titanium alloy. That’s D2794.
• A porcelain-fused-to-metal crown with a base-metal coping. That’s D2751.
• An all-ceramic or all-porcelain crown. That’s D2740.
• A core buildup. That’s D2950.
• A post and core. That’s D2952 (cast) or D2954 (prefab).
• A provisional crown. That’s D2799.

The distinguishing axis: alloy class off the lab invoice

There are four full-cast crown codes, identical except for the alloy class, and that class is a number on the lab invoice. Not the tooth, not the color of the metal.

• D2790 is high noble: at least 60% noble metal with at least 40% gold.
• D2792 is noble: at least 25% noble metal, below the high noble cutoff.
• D2791 is predominantly base metal: under 25% noble metal.
• D2794 is titanium and titanium alloys, a separate material category.

The metals counted toward the percentage are gold plus the platinum group, which the classification of materials lists as platinum, palladium, rhodium, iridium, osmium, and ruthenium. On a base-metal invoice that list is mostly academic, since the practical read is that gold, palladium, and platinum together came to less than a quarter of the casting. A crown lands in D2791 because the invoice shows the casting fell under 25% noble, not because it went on a molar or the alloy looked pale. This full-cast family has a long history of being scrambled by one alloy tier, so the invoice, not recall, sets the code.

Full cast versus PFM: the D2791 and D2751 mix-up

The code most often confused with D2791 is D2751, its porcelain counterpart. D2751 is a PFM crown with a base-metal coping. D2791 is a full-cast base-metal crown. They share the alloy class and both are the budget option, but one has porcelain fused over the metal and one is bare metal.

When to bill D2791

Bill D2791 when:

• The lab fabricates a full-cast crown, all metal with no porcelain.
• The lab invoice confirms a predominantly base-metal alloy (under 25% noble).
• The crown is seated and cemented at the delivery visit.

Do not bill D2791 for:

• A high noble alloy crown. Use D2790.
• A noble alloy crown. Use D2792.
• A titanium or titanium-alloy crown. Use D2794.
• A crown with porcelain on any surface. Use the PFM series, such as D2751 for base metal.
• A provisional or interim crown. Use D2799.
• Recementing an existing crown. Use D2920.

D2791 as the downgrade floor

Because D2791 is the cheapest full-cast alloy tier, it is the fee plans reach for when they downgrade the family. Two patterns show up, and both are plan-dependent:

• Downgrade to D2791 on alloy. A plan pays the predominantly base-metal allowable against a D2790 or D2792 claim, reasoning that any full-cast crown gives the same function regardless of alloy cost. The unpaid difference is not automatically the patient’s, and the contract decides where it lands.
• No downgrade below D2791. When you bill D2791 itself, there is usually nothing cheaper in the full-cast family to drop to. The mistake that costs money runs the other direction: coding D2791 on a crown the lab cast in noble or high noble alloy, where the office collects the base-metal fee on a restoration that cost more to make.

A downgrade is plan design, not a denial, and no appeal overturns it. The EOB shows the billed code, the allowed amount, the plan percentage, and what went unpaid.

Some plans also exclude full-cast crowns entirely and cover only PFM or all-ceramic. On those the denial reads as a non-covered service and the balance falls to the patient, subject to whatever the contract says about fees for non-covered services. Confirm the plan’s crown rules before the prep.

Top reasons D2791 gets denied or reprocessed

1. Construction mismatch with D2751. Billing a full-cast crown as the base-metal PFM code, or the reverse. The alloy class is the same, so the slip alone doesn’t catch it. Only the construction does.
2. Wrong alloy tier. Billing D2791 on a crown cast in noble or high noble alloy underpays the office. Billing D2790 or D2792 on a base-metal crown reprocesses to the D2791 allowable when the invoice is pulled.
3. Frequency limit on a replacement crown. Most plans allow one crown per tooth every 5 to 10 years. A replacement inside the window pends without a narrative documenting the clinical failure on the prior crown.
4. Full-cast exclusion. Some plans cover only PFM or all-ceramic and exclude full-cast crowns outright. The denial reads as a non-covered service.
5. Submitted at the prep visit. Billing before the seat gets the claim rejected or pended. The fee covers the completed, cemented restoration.

Documentation that supports the claim

The claim needs:

• Date of service for the seat visit, not the prep.
• The correct tooth number.
• The alloy confirmation when the carrier requests it, meaning the lab invoice showing the base-metal composition.
• A narrative when the crown is a remake inside the carrier’s frequency window, citing the clinical reason.

For the patient record, keep:

• The lab invoice with the alloy composition. It’s the document that settles an alloy-class dispute and the construction question with D2751.
• Prep, impression, and seat dates.
• The clinical reason for the crown.
• Any prior crown on the same tooth and its placement date.

Example case

A 63-year-old patient has tooth #31 with a fractured lingual cusp and a large failing amalgam. The dentist plans a full-cast crown and, for cost, specifies a base-metal alloy. The lab invoice confirms nickel-chromium, all metal, no porcelain. The plan covers crowns at 50% and, being already at the base-metal tier, applies no further alloy downgrade.

Billing steps:

1. Verify crown coverage, the frequency status on tooth #31, and any waiting period at treatment planning.
2. Read the lab invoice: base-metal alloy, all metal, no porcelain, which puts the crown squarely in D2791 rather than the PFM code D2751.
3. Place a core buildup if the tooth lacks retention and code D2950 separately on the same claim.
4. Submit D2791 at office fee on the seat date, with a one-line narrative on the fracture.
5. Post the carrier’s payment. Because the crown is already base metal and full cast, expect no further material downgrade. Bill the patient the coinsurance and any deductible.

What to get right in your PMS

1. Keep all four full-cast codes as distinct, clearly labeled line items. D2790 high noble, D2792 noble, D2791 base metal, and D2794 titanium should each be their own entry, because this family is miscoded by one alloy tier more than almost any other.
2. Separate the full-cast codes from the PFM codes in the fee schedule. D2791 and D2751 are one keystroke apart in intent and easy to swap. Label them by construction, not just alloy.
3. Tie the code to the lab invoice in the workflow. Confirm the alloy class and the all-metal construction before the claim goes out, not at the prep visit before the lab work is back.
4. Bill at the seat visit, not the prep. Submitting at the prep is a common cause of a rejected or pended claim.
5. Don’t bundle the buildup or post into D2791. Code D2950, D2952, or D2954 separately on the same claim.