D3347 Dental Code: Premolar Root Canal Retreatment

What D3347 covers

D3347 reports nonsurgical endodontic retreatment of a permanent premolar. The tooth’s root canal failed, and the dentist reopens it through the crown, removes the existing filling material, re-cleans and reshapes the canals, and refills them. The buildup and crown that follow are separate codes.

It is retreatment only if the canals were previously obturated. Two cases are not:

• A tooth opened but never filled. If another office accessed, medicated, and temporized the premolar without obturating it, most carriers read the completion as initial therapy under D3320. Get the prior office’s notes before you decide.
• A tooth whose only endodontic history is pulpal therapy. A pulpotomy or pulpectomy on the way to a root canal is not a completed root canal, so the definitive treatment that follows is initial therapy.

The clinical trigger is failure of the first treatment: persistent apical pathology, a canal missed the first time, coronal leakage under a failing restoration, or new decay reaching the canal space. Put that reason in the narrative; it is what the reviewer looks for.

Premolar means eight specific teeth

Retreatment splits on tooth position the same way initial therapy does, and CDT 2026 keeps both series in step:

• D3346 for anterior teeth, matching D3310.
• D3347 for premolars, matching D3320.
• D3348 for molars, matching D3330.

Position, not canal count, picks the code. An upper first premolar with two canals and two roots, a lower second premolar with one canal, and a premolar that took molar-level chair time are all D3347. The root canal dental codes guide sets the retreatment codes beside the first-treatment codes and the waiting windows between them.

Premolars are teeth #4, #5, #12, #13, #20, #21, #28, and #29, and only those belong on a D3347 line. PEHP’s 2026 CDT code guide lists those eight tooth numbers on the D3347 row. Carrier systems compare the tooth number to the tooth type the code implies, so a molar retreatment submitted as D3347, or a premolar as D3348, is rejected before anyone reads the film.

A naming trap in your PMS and in carrier policy

CDT used to call these teeth bicuspids. D3320, D3347, and D3421 switched from “bicuspid” to “premolar” in CDT 2018, but both words are still in use. Your practice management software may carry the old description, so label D3347 with both words in the pick list to make it findable whichever term the user learned.

Many published carrier policies also still print “bicuspid” on the D3347 row, including the Blue Cross & Blue Shield of Rhode Island endodontic policy. If a search for “premolar” in a payer’s policy PDF turns up nothing, search “bicuspid” before concluding the plan has no published rule.

Coverage and how carriers treat retreatment

Retreatment is usually covered on plans that cover endodontics, and it typically pays above initial premolar therapy because the old fill has to come out first. Timing, provider, and frequency decide the claim, and they vary enough that you need to read the specific plan.

The window after the original root canal. Published examples run from 12 to 24 months:

• Blue Cross & Blue Shield of Rhode Island treats retreatment by the same dentist who did the original as integral to it for up to 12 months, and a participating dentist may not bill the member for it.
• EmblemHealth denies D3346, D3347, and D3348 as inclusive of the root canal therapy when billed within 24 months of the initial treatment by the same provider, with no patient liability.
• PEHP writes the limit as a benefit that begins 12 months after completion of the root canal therapy.

Whether the original provider matters. These are not the same rule. The Rhode Island and EmblemHealth policies turn on the same dentist or provider, so a retreatment by a different office can be payable inside the window. PEHP’s language runs on elapsed time only. Don’t assume a different-dentist exception on a plan that never wrote one.

Frequency. Once per tooth for the life of the tooth is the common cap, published that way by both Blue Cross & Blue Shield of Rhode Island and PEHP. A premolar that has already been retreated has usually used its endodontic benefit.

What is bundled. Intraoperative radiographs are part of the procedure on most plans, and the final restoration is always separate. Post removal (D2955) and treatment of an obstructed canal (D3331) are their own codes, but the AAE has cautioned that payers see both filed routinely with retreatment and want documentation proving the case was genuinely difficult.

Documentation that supports the claim

Retreatment claims ask for more than initial therapy, and the extra items are about history:

• The date the original root canal was completed, and who completed it. This resolves the window, and PEHP lists it as required information for D3347. If another office treated the tooth, get the date from the patient or the referring office.
• A pre-op periapical showing the existing fill and the finding that prompted the redo: an apical radiolucency, an untreated canal, or a post under a leaking restoration.
• A post-op periapical showing all canals filled. On an upper first premolar, both canals should be visible when both were treated.
• A narrative of necessity explaining why the first treatment failed. PEHP asks for it in the remarks with a summary of the pre-treatment and post-treatment radiographic findings.
• Tooth identification, the field that trips the tooth-type edit.

Attach the films to the claim, not just the patient chart; the clearinghouse sends only what is linked to the claim. Bill the retreatment on the obturation date and the buildup (D2950) and crown on their own dates, since the same date invites same-day sequencing review at some carriers.

In the chart, record the condition of the previous root canal, what came out of the canals, whether a post or separated instrument had to be removed, how many canals were located including any missed the first time, working lengths, the refill material, and the planned final restoration.

For how the tooth number, the prior treatment date, and the narrative land on the claim itself, see the ADA dental claim form guide.

When retreatment is not the answer

1. The canal cannot be renegotiated. A blocked or heavily calcified canal may be reported with D3331 when the obstruction is real and documented. Treat it as an exception, not a routine add-on.
2. The tooth needs apical surgery instead. A premolar apicoectomy is D3421 for the first root. Upper first premolars are often two-rooted, so a second root treated at the same surgery is D3426. That rarely comes up on anterior teeth and is easy to miss on a premolar claim.
3. The tooth is not restorable. A premolar with a vertical root fracture, insufficient ferrule, or advanced periodontal loss will not hold a new restoration. Some plans deny retreatment on restorability grounds, and a predetermination on a borderline tooth is cheaper than an appeal.