D3320Endodontic Therapy, Premolar Tooth (Excluding Final Restoration)

What This Code Covers

D3320 is the CDT code for a complete root canal on a premolar tooth, also called a bicuspid. Premolars sit between the canines and the molars and typically have one or two root canals, though some upper first premolars can have three. The procedure involves removing diseased or necrotic pulp, cleaning and shaping each canal, and filling them with an obturation material. D3320 carries a higher fee than the anterior code (D3310) because of the added complexity of a possible second canal, but it reimburses less than the molar code (D3330). The final restoration is not included and must be billed separately.

Billing Guide

Bill this code when:

• The dentist completes a root canal on a permanent premolar tooth (teeth 4, 5, 12, 13, 20, 21, 28, 29)
• All phases of endodontic treatment are finished, including access, instrumentation, and obturation
• The tooth has been confirmed as a premolar based on its position and anatomy
• Treatment was performed over one or more visits and the case is now fully completed

Do not bill this code when:

• The tooth is an anterior (incisor or canine), so use D3310 instead
• The tooth is a molar, so use D3330 instead
• The root canal was started but not finished, so use D3331 (incomplete endodontic therapy)
• This is a retreatment of a previously completed root canal on a premolar, which requires D3347

Insurance and Denial Prevention

Key Payer Rules:

• Most PPO and indemnity plans cover D3320 at 80% under major services, subject to the annual deductible
• Some plans apply a different fee schedule for single-canal premolars versus two-canal premolars, but the CDT code is the same regardless
• Waiting periods of 6 to 12 months for endodontic procedures are common on new insurance plans
• A number of payers require preauthorization before beginning root canal therapy on premolars, especially if the tooth already has a large existing restoration

Common Denials and How to Respond:

• Tooth deemed non-restorable --> Submit clinical photographs, the periapical radiograph, and a narrative explaining the tooth's structural integrity and your plan for final restoration. Include the restoration code you intend to bill.
• Downcoded to D3310 (anterior) --> Verify the tooth number is correct on the claim. Include a radiograph that clearly shows the premolar anatomy and its position. If the payer used an incorrect tooth classification, appeal with the ADA tooth numbering chart.
• Preauthorization not obtained --> If the payer requires preauth and it was missed, submit a retroactive authorization request with full documentation. Attach the preoperative radiograph, diagnosis, and clinical notes to support the medical necessity.