Periodontal codes: choosing between D4341, D4342, D4346, D4355 and D4910

Five codes cover most periodontal billing, and the differences between them are diagnostic rather than procedural. Two of them look interchangeable on a schedule and are not, which is where the money goes.

D4346 and D4341 are different diagnoses, not different sizes

This is the single most common periodontal coding error, and it is expensive because it repeats every day.

D4346 covers scaling where there is generalised inflammation but no attachment loss or bone loss — gingivitis in a patient whose supporting structures are intact. D4341 and D4342 cover scaling and root planing, which presumes periodontitis: pocketing, attachment loss, and bone loss that a radiograph can show.

Payers check this against your own chart. Billing D4346 on a patient whose charting shows 5 mm pockets and radiographic bone loss looks like undercoding and often triggers a review. Billing D4341 on a patient with no attachment loss is the denial you will see far more often, and the appeal usually fails because the chart is the payer's evidence, not yours.

D4341 versus D4342 is a tooth count, and it is checked

The split between these two is the number of teeth treated in the quadrant — four or more for D4341, one to three for D4342. It is a mechanical rule and payers audit it mechanically.

• The tooth count in the chart has to match the code billed. Three teeth charted against a D4341 is a straight denial, and it is visible without a human reading anything.
• Quadrants are billed per quadrant. Four quadrants is four line items, not one, and each one needs its own supporting charting.
• Most plans limit scaling and root planing per quadrant on a multi-year cycle, commonly 24 to 36 months. Verification that does not capture the prior date is not verification.

D4355 is diagnostic, and that has consequences

Full mouth debridement exists to let you evaluate a patient whose deposits make evaluation impossible. It is a step before diagnosis, not treatment of a diagnosis.

• A comprehensive evaluation billed the same day is frequently denied or bundled, because the stated purpose of the debridement is to make that evaluation possible later.
• A follow-up evaluation should appear in the record. A D4355 with no subsequent assessment reads as definitive treatment billed under a diagnostic code.
• It is not a substitute for scaling and root planing, and using it that way to avoid the charting requirements of D4341 is the kind of pattern that attracts an audit rather than a denial.

D4910 and the interval that decides it

Periodontal maintenance follows active periodontal therapy. It is not a cleaning with a different number on it, and the distinction from D1110 is where practices lose the most money over time.

• Most payers expect a gap between the completion of scaling and root planing and the first D4910 — 90 days is the common figure, though it is contractual rather than universal.
• Once a patient is in periodontal maintenance, alternating D4910 and D1110 to fit benefit limits is a well-known audit flag. If the patient has periodontitis they have it in March as well as September.
• Some plans cover D4910 under preventive and some under basic, which changes the patient's share substantially. This is worth confirming at verification rather than discovering at checkout.

D4381, which is billed per site

Localised antimicrobial delivery is billed per tooth, not per quadrant or per visit. The documentation that gets it paid is the pocket depth at each treated site and the reason systemic therapy was not the appropriate route. Many plans exclude it entirely, so it belongs on the verification checklist rather than in a hopeful claim.

What to attach before it is denied

1. Complete periodontal charting with pocket depths for the quadrant billed, dated at or before the date of service.
2. Radiographs that show the bone levels the diagnosis relies on.
3. The tooth count per quadrant, matching the code.
4. The date of any prior scaling and root planing, to demonstrate the frequency limit is clear.
5. A short narrative where the clinical picture and the code need connecting — not a template paragraph, which reviewers recognise.