What D3347 means

D3347 covers retreatment of previous root canal therapy on a premolar tooth. "D" is dental, "33" is the root-canal-therapy endodontic group, and "47" is this premolar retreatment. When a premolar that previously had a root canal develops a problem (the root canal fails — persistent/recurrent infection, reinfection, a missed canal, or inadequate prior treatment), retreatment redoes the root canal: reopening the tooth, removing the old root canal filling material, redoing the cleaning, shaping, and disinfection, and resealing the canal(s). D3347 is specifically for retreatment of a premolar (the bicuspids, which usually have one to two canals).

So it's redoing a previously-done root canal on a premolar — reopening it, removing the old filling, re-cleaning, and resealing — to treat a failed prior root canal.

The retreatment codes are divided by tooth type, paralleling the initial root canal codes: D3346 (anterior retreatment), D3347 (premolar retreatment, this code), and D3348 (molar retreatment). Retreatment is used when a previously-root-canaled tooth needs the root canal redone (not for a tooth's first root canal — that's the initial code D3320 for a premolar). Premolar retreatment is intermediate in complexity (the premolar's one to two canals, plus the added work of removing the old filling and addressing the prior failure). It's an alternative to surgery (apicoectomy, D3421 for a premolar) or extraction for a failed root canal, often tried first when feasible. Coverage is under endodontic benefits, with frequency limits; documentation of the prior treatment and the need for retreatment supports the claim.

When it's typically used

D3347 is reported for retreatment of a previous root canal on a premolar tooth — redoing a failed prior root canal (due to persistent infection, reinfection, or inadequate prior treatment) by reopening the tooth, removing the old filling, re-cleaning and disinfecting, and resealing the canal(s). It's distinct from an initial premolar root canal (D3320) and from anterior (D3346) and molar (D3348) retreatments.

How much does D3347 cost?

A premolar retreatment is a moderate fee, often roughly 700 to 1,300 USD depending on region — comparable to or somewhat more than an initial premolar root canal, reflecting the added work of removing the old filling and addressing the prior failure (for the premolar's one to two canals). It excludes the final restoration (separate). It's often performed by an endodontist.

Is D3347 covered by insurance?

Covered under endodontic benefits, with frequency restrictions — most plans cover retreatment once per tooth within a timeframe (commonly a few years). Documentation of the prior root canal (the existing fill on the X-ray), the reason for retreatment, and a narrative supports the claim. It's distinct from an initial root canal (don't rebill D3320 for a tooth that already had one). The final restoration is coded separately. Verifying coverage and providing documentation helps.

Premolar retreatment

Premolar retreatment redoes a premolar's root canal, and understanding it clarifies this procedure.

When a premolar that previously had a root canal develops a problem (the prior root canal failing), retreatment redoes the root canal for that premolar. The reasons a premolar root canal might fail are the same as for other teeth: persistent or recurrent infection, reinfection (e.g., through a leaking restoration or recurrent decay), a missed canal (a premolar can have an extra canal that was missed), or an inadequate prior treatment. When such a problem arises in a previously-root-canaled premolar (with symptoms or findings on X-ray indicating the prior treatment isn't holding up), retreatment is considered to redo the root canal and address the problem.

The premolar retreatment involves redoing the root canal on the premolar's canal(s) (usually one to two) — reopening the tooth, removing the old filling, re-cleaning and disinfecting, addressing the cause of failure (e.g., finding a missed canal), and resealing. The premolar's intermediate canal anatomy (one to two canals) makes its retreatment intermediate in complexity (between anterior and molar retreatments) — plus the added work common to all retreatments (removing the old filling, addressing the failure). So premolar retreatment redoes the premolar's root canal to treat the failed prior treatment. The dentist/endodontist performs the premolar retreatment. For patients, understanding that premolar retreatment redoes a premolar's failed root canal — reopening it, removing the old filling, re-cleaning, addressing the cause, and resealing — clarifies this procedure. It treats a failed prior root canal on a premolar. The dentist or endodontist performs it. Understanding this helps patients see that premolar retreatment redoes the root canal on a premolar whose prior root canal failed (persistent infection, reinfection, a missed canal, etc.) — redoing the treatment on the premolar's one to two canals to address the problem — used when a previously-treated premolar needs its root canal redone to save the tooth.

What retreatment involves

Retreatment involves redoing the root canal, and understanding the process clarifies what's involved.

Retreatment is more involved than the initial root canal because it requires undoing and redoing the prior treatment. For a premolar, the process generally involves: accessing the tooth — reopening the tooth to reach the canal(s), which may involve drilling through a crown or restoration (and removing a post if one was placed); removing the old filling — removing the old root canal filling material (gutta-percha and sealer) from the canal(s), using specific techniques/solvents; re-cleaning and re-shaping — thoroughly cleaning, shaping, and disinfecting the canal(s) again, finding and treating any previously-missed canal (premolars can have an extra canal that was missed); addressing the cause — addressing why the prior treatment failed; refilling and resealing — refilling and resealing the cleaned canal(s); and a temporary restoration (the final restoration being separate). So retreatment disassembles the prior root canal and redoes it.

This added work (removing the old filling, possibly removing a crown/post, finding missed canals, addressing the cause) makes retreatment more technically demanding than the initial root canal. For a premolar (one to two canals), the retreatment is intermediate in complexity (vs. the simpler anterior or the more complex molar retreatment). Finding a missed canal is a common reason for retreatment and an important part of it (an untreated canal can harbor infection, so locating and treating it can resolve the problem). Retreatments are often performed by endodontists given the complexity. After the retreatment, the premolar gets its final restoration (often a crown). The dentist/endodontist performs the retreatment thoroughly. For patients, understanding what retreatment involves — accessing the tooth, removing the old filling, re-cleaning and disinfecting (finding any missed canal), addressing the cause, and resealing — clarifies what's involved. It's redoing the root canal, more involved than the initial one. The dentist or endodontist performs it. Understanding this helps patients see that premolar retreatment redoes the prior root canal — reopening the tooth, removing the old filling, thoroughly re-cleaning and disinfecting (including finding any missed canal), addressing why it failed, and resealing — a more involved procedure than the initial root canal, often done by an endodontist, to properly treat the premolar and clear the problem.

Retreatment vs initial root canal coding

Retreatment is coded differently from an initial root canal, and understanding this clarifies the coding.

Retreatment has its own codes, separate from the initial root canal codes. The initial root canal codes (D3310 anterior, D3320 premolar, D3330 molar) are for a tooth's first root canal. The retreatment codes (D3346 anterior, D3347 premolar, D3348 molar) are for redoing a previously-root-canaled tooth. So for a premolar, the initial root canal is D3320 and the retreatment is D3347 (this code). It's important not to use the initial code (D3320) for a retreatment — a premolar that already had a root canal, being redone, uses D3347, not D3320 again.

This distinction matters for coding and insurance. Insurance typically covers an initial root canal once per tooth (per lifetime), so billing the initial code (D3320) again on a tooth that already had a root canal would be denied (a frequency-limit denial) — the retreatment code (D3347) is used instead. Carriers can see the prior root canal on the pre-op X-ray (the existing fill), so coding a retreatment as an initial root canal gets caught. Retreatment also has its own frequency considerations (often covered once within a timeframe). So the dentist checks whether the premolar already had a root canal (via the X-ray/history) and uses the retreatment code (D3347) for a retreatment, not the initial code. The dentist uses the correct code based on whether it's an initial treatment or a retreatment. For patients, understanding that retreatment (D3347) is coded differently from an initial root canal (D3320) clarifies the coding. The retreatment has its own code, not the initial one. The dentist codes by whether the tooth had a prior root canal. Understanding this helps patients see that redoing a premolar's root canal is coded D3347 (retreatment), not D3320 (the initial code) — so the code reflects that it's a retreatment of a previously-treated tooth, with its own coverage considerations (e.g., frequency limits on retreatment), distinct from the initial root canal coding.

Saving the tooth with retreatment

Retreatment aims to save the tooth, and understanding this clarifies its value among the options.

Retreatment aims to save a tooth whose root canal has failed — by redoing the root canal properly to clear the problem, allowing the tooth to be kept (rather than extracted). For a failed root canal, the options are retreatment (redo from inside), apical surgery (apicoectomy, D3421 for a premolar — treating the root tip surgically), or extraction (removing the tooth). Retreatment is often the first option considered when feasible, because it's non-surgical and aims to save the natural tooth by properly redoing the root canal (addressing the cause of failure, like a missed canal or persistent infection). Saving the natural tooth (via retreatment) is generally preferable to extracting it (and needing a replacement like an implant or bridge), when the retreatment has a good prognosis.

So retreatment's value is in offering a way to save a tooth with a failed root canal — giving the tooth another chance by redoing the root canal. When successful, the retreatment clears the problem and the tooth (with its final restoration, often a crown) can function long-term. If retreatment isn't feasible or doesn't resolve the problem, surgery (apicoectomy) or extraction are the alternatives. The dentist/endodontist assesses whether retreatment is feasible and has a good prognosis (worth trying to save the tooth), recommending it when appropriate. So retreatment is a tooth-saving option for a failed root canal. For patients, understanding that retreatment aims to save the tooth — by redoing the failed root canal properly, an alternative to extraction — clarifies its value. It gives the tooth another chance, preserving the natural tooth when feasible. The dentist/endodontist recommends it when appropriate. Understanding this helps patients see that retreatment offers a way to save a premolar with a failed root canal — redoing the root canal to clear the problem and keep the natural tooth — often preferable to extraction (and a replacement) when the retreatment has a good prognosis, with surgery or extraction as alternatives if retreatment isn't feasible or doesn't succeed.

Frequently asked questions

What is the D3347 dental code?

It's retreatment of a previous root canal on a premolar (bicuspid) tooth — redoing a root canal that was done before but failed (due to persistent infection, reinfection, or inadequate prior treatment). It involves reopening the tooth, removing the old filling, re-cleaning and disinfecting, and resealing the canal(s).

When does a premolar root canal need redoing?

When a previously-treated premolar has persistent or recurrent infection, reinfection, a missed canal (premolars can have an extra canal that was missed), or an inadequate prior treatment — with symptoms or X-ray findings indicating the prior treatment isn't holding up. Retreatment redoes the root canal to address this.

How is retreatment different from a regular root canal?

Retreatment is more involved — reopening the tooth (sometimes through a crown), removing the old filling, re-cleaning and disinfecting (finding any missed canal), addressing why the prior treatment failed, and resealing. It redoes the prior treatment, more demanding than the initial root canal.

Why is retreatment coded D3347 and not D3320?

D3347 is the retreatment code for a premolar; D3320 is the initial root canal code. A premolar that already had a root canal, being redone, uses D3347 (not D3320 again). Rebilling D3320 on an already-treated tooth would be denied; carriers see the prior fill on the X-ray.

How much does premolar retreatment cost?

Often around 700 to 1,300 USD, comparable to or somewhat more than an initial premolar root canal, reflecting the added work of removing the old filling and addressing the prior failure. It excludes the final restoration (separate) and is often done by an endodontist.

Is retreatment worth it vs extraction?

Retreatment aims to save the natural tooth by redoing the root canal, often preferable to extraction (and needing a replacement like an implant or bridge) when it has a good prognosis. It's often tried first when feasible; surgery (apicoectomy) or extraction are alternatives if retreatment isn't suitable.

This page is an independent, plain-language explanation for general information only. It is not billing, coding, or clinical advice. For the official CDT descriptor and current-year wording, refer to the American Dental Association.