D3320 is the CDT code for endodontic therapy on a premolar tooth — a root canal on a bicuspid — excluding the final restoration. It covers the complete root canal (access, cleaning and shaping of the canals, and obturation) on a premolar, but not the crown or filling that restores the tooth afterward, 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 D3320 Code
Report D3320 when a dentist performs complete endodontic treatment on a premolar (bicuspid). It applies when the pulp is irreversibly inflamed or necrotic — commonly from deep decay, a fracture, trauma, or a failing large restoration — and the tooth is being saved rather than extracted.
Use the matching code for the tooth type: D3310 for anterior teeth and D3330 for molars. Premolars typically have one or two canals, placing them between anterior and molar teeth in complexity, which is why they're coded separately. Note that re-treatment of a previously treated premolar is D3347 (retreatment, premolar), not D3320, and surgical and retrograde procedures have their own codes.
Documentation & Clinical Scenarios
Clean documentation supports medical necessity and identifies the tooth:
- Tooth number and a clear diagnosis (e.g., irreversible pulpitis, pulpal necrosis, symptomatic apical periodontitis).
- Pre-operative radiograph(s) showing the condition, often with a post-operative film confirming the fill.
- Procedure detail — number of canals located and treated, working length, and obturation.
- A narrative when complications arise (an extra canal, calcified or curved canals) or when the payer requests one.
Because the final restoration is excluded, the crown or buildup is documented and billed under its own code. A typical sequence is D3320, then a core buildup (D2950) if needed, then a crown such as D2740 or D2750.
Insurance & Billing Tips
- Verify benefits first. Confirm endodontic coverage, the remaining annual maximum, any waiting period, and whether a pre-treatment estimate is recommended.
- Bill the restoration separately. D3320 never includes the crown or filling — report the restoration on its own line so neither is denied for bundling.
- Watch frequency and history. If the tooth was treated before, the correct code is the re-treatment code (D3347), and claiming D3320 may trigger a denial.
- Read the EOB carefully. If a premolar canal is down-coded or denied, a short narrative plus the pre-op radiograph supports an appeal.
- Coordinate the timeline. Some plans want the root canal and the crown within a defined window; check before scheduling the restorative visit.
Example Case
A 50-year-old established patient calls with lingering cold sensitivity and pain on biting in an upper tooth "about halfway back." The dentist diagnoses irreversible pulpitis on tooth #12 (a premolar), confirmed by a periapical radiograph. Endodontic therapy is completed across the canals and documented with a post-op film — reported as D3320. The tooth is later restored with a core buildup and a crown, each billed under its own code. Because the office verified benefits and billed the restoration separately, both claims process without a bundling denial.
On the phone, patients don't say "D3320" — they say a tooth halfway back is throbbing. DentalReception AI answers those calls in under two rings, 24/7, captures the symptom and urgency 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
How is D3320 different from D3310 and D3330?
All three are root canals; the difference is the tooth. D3310 is for anterior (front) teeth, D3320 is for premolars (bicuspids), and D3330 is for molars. Premolars have one or two canals, putting them between the single-canal anteriors and the more complex molars, which is why each tooth type has its own code. Using the wrong tooth-type code is a common error that can cause a denial or down-code.
Does D3320 include the crown or final restoration?
No. D3320 is the endodontic therapy on the premolar only and explicitly excludes the final restoration. The crown, filling, or core buildup that rebuilds the tooth afterward is reported separately under its own CDT code. Billing them on the same line is a common cause of bundling denials, so the restoration should always appear on its own line with its own code.
Can D3320 be used to re-treat a premolar that already had a root canal?
No. Re-treatment of a previously treated premolar is reported with D3347 (retreatment, premolar), not D3320. Using D3320 for a re-treatment typically results in a denial, so confirm the tooth's endodontic history before coding. The re-treatment codes exist because reworking a previously filled canal is a different, often more involved, procedure than an initial root canal.
Does D3320 require a pre-authorization?
A pre-authorization isn't always required, but a pre-treatment estimate with the pre-operative radiograph is often recommended. It confirms the patient's remaining benefit, any waiting period, and the expected coverage, reducing the chance of a denial or a surprise balance. Since endodontic therapy is a higher-cost procedure that payers frequently review, verifying benefits before treatment protects both the office and the patient.
Confirm the current CDT descriptor and your specific payer policies before billing — browse the full dental code library or see our insurance verification feature.