D3347 is the CDT code for the retreatment of previous root canal therapy on a premolar tooth — redoing a failed or failing root canal on a bicuspid. It covers removing the prior root canal filling, re-cleaning and re-shaping the canals, and re-obturating them, excluding the final restoration, which is reported separately.
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 D3347 Code
Report D3347 when a dentist re-treats a premolar that has had a prior root canal — typically because of persistent or recurrent infection, a missed canal, a failed obturation, or new decay compromising the seal — and the tooth is being saved rather than extracted.
The distinguishing factor is the prior treatment. An initial root canal on a premolar is D3320 (endodontic therapy, premolar), not D3347; use the retreatment code only when there's a documented previous root canal. Match the tooth type as well: D3346 is retreatment of an anterior tooth and D3348 is retreatment of a molar. If a surgical approach is needed instead of a non-surgical redo, an apicoectomy code applies.
Documentation & Clinical Scenarios
Retreatment claims hinge on showing the prior treatment and the reason for redoing it:
- Tooth number and documentation that a previous root canal exists on that tooth.
- The reason for retreatment — persistent symptoms, periapical radiolucency, a missed or under-filled canal, or a failed seal.
- Pre-operative radiograph(s) showing the existing fill and the failure, often with a post-op film.
- Procedure detail — removal of the prior filling material, re-cleaning, and re-obturation of the canals.
Because the final restoration is excluded, any new crown or buildup is documented and billed under its own code, and a narrative is often expected to justify the redo.
Insurance & Billing Tips
- Verify benefits and history. Confirm endodontic retreatment coverage and any waiting period; some plans limit how soon a tooth can be re-treated after the original therapy.
- Document the prior treatment. A retreatment claim should show the tooth was previously root-canaled; without it, the payer may question the code.
- Use the right code. D3347 is for premolar retreatment only — D3346 (anterior) and D3348 (molar) apply to other teeth; an initial canal is D3320.
- Bill the restoration separately. Any new crown or buildup is its own line, never bundled into D3347.
- Expect to appeal. Retreatments are reviewed closely; a narrative plus the pre-op radiograph showing the failure supports the claim.
Example Case
A 47-year-old established patient reports a premolar that "never fully settled" after a root canal two years ago and has started aching on biting again. A periapical radiograph of tooth #4 shows a persistent periapical lesion. The dentist removes the old filling material, re-cleans and re-fills the canals, and documents the failure and the redo — reported as D3347. The tooth is later restored under its own code. Because the office documented the prior root canal and the reason for retreatment and attached the radiograph, the claim is supported through review.
On the phone, patients don't say "D3347" — they say a treated tooth halfway back is bothering them again. DentalReception AI answers those calls in under two rings, 24/7, captures the symptom and history in the patient's words, and books the visit live into your schedule — while every clinical and coverage decision routes to your team. See how it handles root canal calls, or book a demo.
Frequently Asked Questions
What's the difference between D3347 and D3320?
D3347 is the retreatment of a premolar that already had a root canal, while D3320 is the initial endodontic therapy on a premolar. The retreatment code applies only when there's a documented previous root canal being redone. Billing D3320 for a redo — or D3347 for a first-time canal — is a common error, so confirm the tooth's endodontic history before selecting the code.
How is D3347 different from D3346 and D3348?
All three are endodontic retreatment codes; the difference is the tooth. D3346 is for anterior (front) teeth, D3347 for premolars, and D3348 for molars. The procedure is reworking a previously treated canal, but each tooth type is reported separately because complexity differs — premolars sit between single-canal anteriors and multi-canal molars. Using the wrong tooth-type retreatment code can cause a denial or down-code.
Does D3347 include the new crown or restoration?
No. D3347 covers the endodontic retreatment of the premolar only and excludes the final restoration. Any new crown, buildup, or filling placed after the retreatment is reported separately under its own CDT code. Billing the restoration on the same line as the retreatment is a common cause of bundling denials, so it should always be reported on its own line.
Does D3347 require a pre-authorization?
Retreatment is reviewed more closely than an initial root canal, so a pre-treatment estimate is often recommended even when a formal pre-authorization isn't required. Confirming retreatment coverage and any waiting period, and documenting the prior root canal with a radiograph showing the failure, both lowers the chance of a denial and provides the basis for an appeal if the claim is questioned.
Confirm the current CDT descriptor and your specific payer policies before billing — browse the full dental code library or see our insurance verification feature.