D2991 Dental Code: Hydroxyapatite Regeneration Billing

What D2991 covers

D2991 reports applying a hydroxyapatite regeneration medicament to one tooth. The procedure involves preparing the tooth surface and placing a medicament that forms a scaffold on an early, non-cavitated lesion. The scaffold draws calcium and phosphate back into the enamel so the affected surface rebuilds, rather than the clinician simply slowing the decay or filling the tooth. It is reported per tooth, so two treated teeth means two units.

The clinical idea is newer than most codes on a fee schedule. Products built for this approach, such as Curodont Repair and CrystLCare, are guided enamel-regeneration medicaments aimed at incipient lesions and white-spot demineralization. D2991 is the code that lets a practice report that work as its own line item instead of forcing it into a fluoride or restoration code that doesn’t describe it.

D2991 does not cover:

• A caries-arresting medicament like silver diamine fluoride. That’s D1354.
• A preventive medicament on a tooth with no lesion. That’s D1355.
• Topical fluoride varnish (D1206) or non-varnish topical fluoride (D1208).
• A filling or an interim restoration. An interim direct restoration that protects the tooth until definitive treatment is D2940. A definitive filling is its own restorative code.

The distinguishing axis: regenerate, not arrest, not prevent

This is the thing to get right on D2991, and the thing most likely to get coded wrong. The medicament codes near it all involve painting something onto a tooth without drilling, so they look interchangeable. They are not. The line between them is what the medicament does to the lesion.

• D1355 is prevention. The tooth has no lesion yet, and the medicament is applied to keep one from forming or to remineralize a surface at risk. It excludes topical fluorides.
• D1354 is arrest. There is an active lesion, and the medicament, commonly silver diamine fluoride, halts its progression without removing sound tooth structure. It stops the decay. It does not rebuild the tooth.
• D2991 is regeneration. There is an early lesion, and the medicament forms a scaffold that rebuilds the affected enamel. It goes past arrest to actually restoring the surface, which is why the code lives in the restorative section, not preventive.

So the sequence is prevent (D1355), arrest (D1354), regenerate (D2991), and the right code follows the clinical goal for that tooth. It is not the patient’s age, the tooth number, or the brand of material that picks the code. It is whether you’re keeping a lesion from starting, stopping one that’s active, or rebuilding enamel on an early one.

Coverage reality: a new code many plans haven’t adopted

The biggest billing trap on D2991 is treating an active code as a covered benefit. It is active, but hydroxyapatite regeneration is a recent category of care, and a meaningful number of plans still classify it as not a benefit or as experimental and decline to pay. An eligibility check that confirms the code exists tells you nothing about whether this plan pays it.

When a plan does cover D2991, the terms vary by contract:

• Frequency caps. Some plans that pay it limit it per tooth per benefit year. The cap and the counting method are plan-specific.
• Bundling with restorations. A common rule is that the regeneration medicament is not separately payable when a restoration is placed on the same tooth on the same date, and sometimes not when a restoration follows within a set window. This is contract language, not a clinical judgment.
• Patient responsibility. Where the plan doesn’t cover it or bundles it away, the patient generally owes the fee, subject to your participating-provider agreement. Because patients don’t expect to pay for a “no-drill” treatment, set that expectation before you provide it, not after the EOB.

When to bill D2991

Bill D2991 when the clinician applies a hydroxyapatite regeneration medicament to a single tooth with an early, non-cavitated lesion to rebuild the affected enamel. Report it once per treated tooth.

Do not bill D2991 for:

• Arresting an active lesion with silver diamine fluoride. That’s D1354.
• A preventive medicament on a tooth with no lesion. That’s D1355.
• A topical fluoride application, varnish (D1206) or otherwise (D1208).
• A filling or an interim restoration on the tooth. Use the appropriate restorative code, such as D2940 for an interim direct restoration.

Documentation that supports the claim

Because D2991 is new and often reviewed by hand, the record needs to make the case that this was regeneration on an early lesion, not a fluoride application or an arrest. The chart should show:

• The lesion status. Document that the tooth had an early, non-cavitated lesion or white-spot demineralization, with the tooth number and surface noted.
• The treatment goal. State that the intent was enamel regeneration, which separates it from D1354 (arrest) and D1355 (prevention).
• The medicament used. Name the product applied so the procedure matches a guided hydroxyapatite regeneration medicament.
• Supporting images where available. A pre-treatment radiograph or intraoral photo of the lesion strengthens a claim a carrier is likely to scrutinize on a newer code.

If the plan requires prior authorization for newer non-restorative procedures, get it before treatment. A claim for a code the carrier hasn’t fully adopted is more likely to pend or deny without it.

What to get right in your PMS

The menus differ across Open Dental, Dentrix, Eaglesoft, Curve, and Carestream, but the setup that prevents miscodes is the same:

1. Add D2991 as its own line item, distinct from the medicament codes near it. Keep D2991, D1354, and D1355 as separate, clearly labeled codes so picking one is a deliberate choice. They describe different clinical goals and live in different CDT sections.
2. Don’t default it to “covered” in your fee and estimate setup. Because adoption is uneven, set the patient estimate to reflect that the plan may not pay it, then update once you’ve verified the specific benefit.
3. Flag the same-tooth bundling rule. If your system can note plan rules, record that some carriers won’t pay D2991 separately when a restoration is placed on the same tooth, so the estimate doesn’t double-count.
4. Capture lesion status and the medicament in the note at the time of treatment. That single detail is what defends D2991 against a “should have been D1354” or “should have been a fluoride code” review.
5. Set the patient-responsibility expectation up front. For a treatment patients assume is free or covered, the financial conversation belongs before the appointment, not after the EOB posts.