You opened a treatment plan or an EOB and saw cryptic codes like D3330 or D3346. This page explains what each of the endodontic codes actually means, why some cost more than others, and how to read the line items on your insurance statement — without the billing-office jargon.
Reviewed by Dr. Jason Kung, DDS, MS — Specialist Endodontist · UCLA DDS · OHSU MS
These plain-English explanations paraphrase the ADA CDT terminology so patients can understand their own treatment plans. For the official, copyrighted ADA definitions, see the ADA CDT glossary.
Every code below is a current ADA CDT code that an endodontist or general dentist may use on a treatment plan, insurance pre-determination, or EOB. The "What it means" column is a plain-English paraphrase — not the official ADA definition.
| Code | Procedure | What it means | When it applies |
|---|---|---|---|
| D3310 | Root canal on a front tooth | Root canal treatment on an incisor or canine. One canal in most cases, so it's typically the simplest and least expensive of the three primary root canal codes. | Front teeth with irreversible pulpitis, a dead nerve, or an abscess at the root tip. Does not include the final crown or filling — that's billed separately by your general dentist. |
| D3320 | Root canal on a premolar (bicuspid) | Root canal treatment on a premolar (the small chewing teeth between your canines and molars). Usually one or two canals; some upper first premolars have two roots. | Premolars (also called bicuspids) needing root canal treatment. Extra canal anatomy is included in this single code. |
| D3330 | Root canal on a molar | Root canal treatment on one of the large back chewing teeth. Three to four canals on average, often more — molars are the most complex and time-consuming root canal to treat. | 1st, 2nd, or 3rd molars needing root canal treatment. The MB2 canal in upper molars and curved or calcified canals are common reasons these cases are referred to a specialist. |
| D3346 | Redoing a previous root canal — front tooth | Reopening and redoing a root canal on a front tooth that was treated before but failed (persistent infection, new symptoms, or a leaky restoration). Generally more complex than the original because old filling material must be removed first. | An anterior tooth with a prior root canal that hasn't healed, has new symptoms, or is at high risk of recontamination before placing a new crown. |
| D3347 | Redoing a previous root canal — premolar | Reopening and redoing a root canal on a premolar. Requires disassembling the previous treatment, often through a crown, before the new disinfection can begin. | A premolar with a failing or symptomatic prior root canal where retreatment offers a better long-term outcome than extraction. |
| D3348 | Redoing a previous root canal — molar | Reopening and redoing a root canal on a molar. The most technically demanding non-surgical endodontic procedure — typically performed by an endodontist using a microscope and CBCT. | A molar with a failing prior root canal — missed canal, persistent infection at the root tip, leakage under an old filling, or a new crown about to be placed over a marginal root canal. |
| D3410 | Root-tip microsurgery — front tooth | Microsurgical removal of the very tip of a front tooth's root, with a small filling placed at the cut root end to seal the canal from the outside. Performed when a non-surgical retreatment isn't possible or hasn't worked. | A front tooth with persistent infection at the root tip that can't be reached through the crown. Often follows a prior root canal protected by a post or crown that can't be safely removed. |
| D3421 | Root-tip microsurgery — premolar (first root) | The same root-tip microsurgery as D3410, but on a premolar. Each additional root on the same tooth is billed under D3426. | A premolar with persistent infection around the root tip after a prior root canal. |
| D3425 | Root-tip microsurgery — molar (first root) | Root-tip microsurgery on a molar. Technically the most challenging because of root proximity to the sinus (upper molars) or the inferior alveolar nerve (lower molars). | A molar with persistent infection at the root tip where retreatment isn't feasible. Modern microsurgery (microscope, ultrasonic root-end preparation, bioceramic seal) has substantially improved outcomes over older techniques (Setzer et al., J Endod 2010 meta-analysis). |
| D3426 | Root-tip microsurgery — each additional root | An add-on code billed alongside D3421 or D3425 when more than one root on the same tooth needs surgery. Most upper molars have three roots; if two are involved, you'll see D3425 plus D3426. | Multi-rooted teeth (premolars or molars) where the infection involves more than one root. |
| D3220 | Pulpotomy (partial nerve removal) | Partial removal of the inflamed nerve tissue from the crown of the tooth, leaving the healthy root nerve intact. Often used as a bridge step on a tooth that may or may not need full root canal treatment later. | Performed on a tooth with reversible or early irreversible pulpitis as a vital pulp therapy, especially in young patients with immature roots, or as an interim step before definitive root canal treatment. |
| D3221 | Emergency nerve removal | Same-day removal of the infected nerve to relieve severe pain when full root canal treatment can't be completed that day. The tooth is medicated and sealed temporarily — you'll return to finish the root canal. | Same-day emergency visits for severe pulpal pain or acute abscess. We open the tooth, clean out the infected nerve, and place medication; the full root canal (D3310/D3320/D3330) is billed at the follow-up appointment. |
| D0367 | Small-volume 3D dental scan (CBCT) | A small, low-dose three-dimensional X-ray focused on a single tooth or one section of the jaw. Used to find hidden canals, diagnose cracks, or plan complex retreatments and microsurgery. | Endodontic diagnosis when 2D X-rays don't tell the full story. The AAE/AAOMR Joint Position Statement on CBCT in Endodontics (2015) supports small-volume scans for these cases. |
| D9230 | Nitrous oxide (laughing gas) | Inhaled nitrous oxide to reduce dental anxiety. Wears off in minutes after the mask comes off — you can drive yourself home. | Anxious patients who prefer light, breath-in/breath-out anxiety relief. (Our office does not offer IV sedation; if you need deep sedation, your general dentist can refer you to a practice that does.) |
Why your dentist's code list may differ
Crowns, build-ups, posts, and core restorations are billed by your general dentist under separate codes (D2950, D2954, D2740, etc.) once endodontic treatment is complete. The codes above cover only the endodontic portion. If you want a single line-by-line cost breakdown that combines our work and your general dentist's restorative work, we're happy to coordinate that on a phone call.
Your Explanation of Benefits (EOB) is the statement your insurance sends you after a claim is processed. Each line shows: the date of service, the CDT procedure code, the dentist's submitted fee, the amount your insurance allowed under your plan, the percentage they paid, and what's left for you. Common things to look for:
All dental procedure codes are part of the ADA Current Dental Terminology (CDT) code set, updated annually. Insurance companies use these codes to determine coverage and reimbursement. The official, copyrighted ADA CDT glossary is published at ada.org.
Molars typically have three to four canals (sometimes more) versus a single canal in most front teeth, take roughly twice as long to treat, and require more advanced anatomy mapping (microscope, CBCT, MB2 location). Insurance and ADA fee surveys reflect this complexity.
Retreatment requires disassembling the previous root canal — drilling through a crown, removing posts, dissolving old root filling material, then redoing the entire disinfection and obturation. It's the most technically demanding non-surgical endodontic procedure and is almost always performed by an endodontist.
Both address a failed root canal. D3346 (non-surgical retreatment) reopens the tooth through the crown and redoes the root canal from the inside. D3410 (apicoectomy) is a microsurgical procedure that removes the root tip and seals the canal from the outside through a tiny gum incision. We recommend retreatment first when it's feasible, and surgery when retreatment isn't possible or hasn't resolved the infection.
Most PPO plans cover endodontic treatment at the major service tier (often 50–80% after deductible), subject to your annual maximum, frequency limitations, and missing-tooth or alternate-benefit clauses. We verify benefits and provide a written estimate before any procedure — call (669) 234-2354 or email us your insurance card.
Older CDT versions had per-canal add-on codes; the current CDT bundles canal complexity into the single endodontic therapy code (D3310/D3320/D3330). For surgery, each additional root on the same tooth is billed under D3426. If you see unfamiliar add-on codes on a claim, ask your provider to walk you through the breakdown.
This page is patient education only — definitions are plain-English paraphrases and may simplify clinical nuance. CDT codes and definitions are © American Dental Association; consult the official ADA CDT glossary for authoritative terminology. Insurance reimbursement, allowed amounts, and coverage rules vary by plan and are not determined by this office.
Email a photo of the treatment plan and the most recent X-ray to siliconvalleyendo@gmail.com — we'll review the codes and the proposed treatment, and tell you honestly whether a root canal, retreatment, apicoectomy, or extraction is the best path forward for that tooth.