D5120Complete Denture, Mandibular

What This Code Covers

D5120 covers a complete removable denture for the lower arch, replacing all teeth in the mandibular jaw. The code includes the entire fabrication process from initial impressions through final delivery, plus adjustments for six months after placement. Lower dentures are generally more challenging to fit than upper dentures because the mandibular ridge provides less surface area for suction and stability. Lab fees, denture teeth selection, and routine post-delivery adjustments are all included and should not be billed separately.

Billing Guide

Bill this code when:

• Patient has lost all lower teeth and a full mandibular denture is fabricated and delivered
• All lower teeth were previously extracted and tissue has healed sufficiently for final impressions
• The denture is a conventional (not immediate) complete lower denture
• The patient is receiving a replacement complete mandibular denture because their existing lower denture is worn, broken, or no longer fits

Do not bill this code when:

• The denture is placed on the same day as extractions. Use D5140 (immediate denture, mandibular) instead
• The patient still has some natural lower teeth remaining. Use a partial denture code such as D5214
• The denture is for the upper jaw. Use D5110 (complete denture, maxillary)
• The denture is an implant-supported overdenture. Use the appropriate implant overdenture code such as D6111

Insurance and Denial Prevention

Key Payer Rules:

• Classified as major prosthodontics, typically covered at 50% after deductible
• Most plans impose a 12-month waiting period for major prosthodontic services for new members
• Replacement frequency is usually limited to once every 5 to 10 years per arch
• Some payers require documentation that the patient has attempted other retention options before approving a conventional lower denture
• Pre-authorization is strongly recommended. Submit a panoramic radiograph and narrative explaining the clinical need
• Payers may question why an implant-retained overdenture was not considered for the lower arch, especially for patients with severe ridge resorption

Common Denials and How to Respond:

• Frequency limitation not met -> Appeal with clinical notes, photos, and radiographs showing the current denture is damaged, ill-fitting, or causing soft tissue problems. Document failed repair attempts if applicable.
• Pre-authorization missing -> Submit the claim retroactively with complete documentation. Include a narrative explaining why prior authorization was not obtained (patient urgency, delayed coverage verification, etc.).
• Insufficient documentation of edentulous status -> Provide a clear panoramic radiograph showing no remaining mandibular teeth. Include extraction records with dates if the teeth were recently removed.
• Alternate benefit applied (implant overdenture recommended) -> If the payer downgrades or denies in favor of an implant option, clarify the patient's clinical situation. Some patients are not candidates for implants due to bone loss, medical conditions, or financial constraints.