These two get mixed up constantly, and the mistake is expensive in both directions. Bill a prophy when you did periodontal maintenance and you underpay yourself. Bill maintenance when the plan will not cover it and the claim bounces. The line between them is not the patient's history alone, it is what you actually do at the visit. This guide draws that line and shows how to keep D4910 paid.
Last updated July 2026 · Reviewed by the PracticeAlpha billing team
The short answer. A prophylaxis (D1110) is a preventive cleaning for a patient with a healthy periodontium. Periodontal maintenance (D4910) is the recall visit for a patient who has already had active periodontal therapy, and it includes site-specific subgingival instrumentation plus a perio evaluation, not just a polish. You code the visit for what you clinically perform. The billing headaches, denials, downgrades, and the "can I alternate them" question, all come from trying to make the clinical reality fit the plan's rules instead of the other way around.
D1110 is preventive. It is the standard adult cleaning for a patient whose gums are healthy, or who has localized gingivitis at most. Supragingival scaling and polishing, no active disease being treated. If your patient has never had periodontal disease, this is the code for their recall.
D4910 is therapeutic. It is for a patient who has completed active periodontal treatment, scaling and root planing (D4341 or D4342) or periodontal surgery, and is now in an ongoing maintenance program. The visit is more than a cleaning: it involves site-specific subgingival instrumentation on the pockets that remain, plus a periodontal reassessment. The point is to keep stabilized disease from progressing.
So the real question at any given recall is not "is this patient a perio patient forever." It is "what does this specific visit involve." That distinction is where the coding, and the denials, live.
A lot of offices believe that once a patient starts on D4910, they can never be billed a prophy again. That is a myth, and the ADA's own coding guidance retired it. Having had periodontal therapy does not lock a patient into maintenance for life.
If a maintenance patient's tissue stabilizes to the point where a recall needs only a routine supragingival cleaning with no subgingival work, then that visit is a prophylaxis and D1110 is the honest code for it. If instead the visit requires site-specific subgingival instrumentation, it is maintenance and it stays D4910. The clinical reality at the chair decides, not a permanent label on the chart.
Yes, but only for the right reason. The codes are not mutually exclusive, and the ADA has said so plainly: nothing in D4910, D1110, or D1120 makes them incompatible. A patient can legitimately move between maintenance and prophy visits as their periodontal status changes.
The line you cannot cross is alternating to game a frequency cap. Some plans only cover so many maintenance visits a year, so the temptation is to bill a prophy on the off visits to squeeze out another paid cleaning. If the visit was actually a maintenance visit with subgingival instrumentation, recoding it as a prophy to fit the plan misrepresents the service. Code what you did. Let the plan sort out its own benefit.
Perio maintenance denials almost always trace back to something that should have been caught before the visit, coverage, frequency, or missing perio history. We check all of it during verification.
See our verification serviceNo prior perio therapy on file. Carriers want proof the patient earned maintenance status. If the scaling and root planing that qualifies them is not documented with the payer, the SRP codes and their dates, the maintenance claim gets denied. This is the single biggest cause, and it bites hardest when a patient transfers in from another practice.
The waiting period. Most plans require roughly eight to twelve weeks between the completion of active periodontal therapy and the first D4910. Bill inside that window and it bounces.
Frequency caps. Many carriers cover maintenance up to four times a year, some fewer, and some count prophy and maintenance visits against a shared limit. Once the cap is hit, further visits are denied or paid down.
A prophy billed earlier in the cycle. On some plans, once a D1110 is submitted, subsequent D4910 claims in the same period are nullified. The sequence of what you billed can quietly disqualify the code you need next.
Frequency rules are entirely plan-specific, which is why guessing is a losing game. Some plans allow four maintenance visits a year, some alternate maintenance with a prophy, some fold both into one shared count. The only reliable number is the one you get by verifying the individual patient's benefits before the appointment.
When a plan will not pay D4910 at all, or downgrades it, do not recode. Keep the visit coded as the maintenance it was, and let the carrier apply its alternate benefit at the prophylaxis allowance. You can add a short statement to the claim asking that, if maintenance is denied, the plan apply the prophy benefit that is included within it. Then bill the patient the difference. That keeps you honest, keeps the visit correctly documented, and still collects something toward the work.
To bill maintenance cleanly, make sure the patient's periodontal history is on file with the carrier, the qualifying SRP and its dates are documented, and current perio charting supports the visit. Get those three in place before the claim goes out and most D4910 denials disappear.
Perio maintenance is a small code with an outsized denial rate, because getting it paid depends on three things happening before the hygienist ever picks up an instrument: coverage confirmed, frequency checked, and perio history established with the carrier. On a busy front desk, one of those slips, and the claim comes back weeks later.
That is the gap a dedicated billing team closes. Benefits and frequency get verified ahead of the visit, the perio history gets established with the payer up front, and when a plan downgrades, the alternate benefit gets pursued and the patient portion billed correctly instead of written off. If you want to see how much recall revenue is leaking to preventable denials, start with a free AR analysis and we will show you where it is going.
D1110 is a routine preventive cleaning for a patient with a healthy periodontium. D4910 is periodontal maintenance, the recall visit for a patient who has already had active periodontal treatment such as scaling and root planing or perio surgery. D4910 includes subgingival and site-specific instrumentation on residual pockets plus a periodontal evaluation, not just a supragingival polish. The deciding factor is the patient's periodontal history and what you actually do at the visit.
Yes, when it is clinically justified. The ADA's coding guidance is clear that D4910, D1110, and D1120 are not mutually exclusive. If a maintenance patient's periodontal health improves so a visit needs only a routine prophy with no subgingival scaling, D1110 is appropriate. What you cannot do is flip between the codes just to fit a plan's frequency cap. Code for what you clinically perform.
No, and the ADA's own coding companion put that myth to rest. Having had periodontal therapy does not mean a patient can never receive a prophylaxis again. If the tissue has stabilized and a visit involves only supragingival cleaning, a prophy is correct for that visit. If the visit includes site-specific subgingival instrumentation, it is periodontal maintenance. The clinical picture decides, not a permanent label.
The most common reasons are that the carrier has no record of prior active periodontal therapy, the visit falls inside the waiting period after that therapy, a frequency cap has been hit, or a prophy was billed earlier and the plan now treats maintenance as ineligible. Missing documentation of the prior scaling and root planing and its dates is the single biggest cause.
It varies by carrier. Many plans cover D4910 up to four times a year, some alternate it with a prophy, and most require a waiting period of roughly eight to twelve weeks after the active periodontal therapy is completed. Because every plan is different, the reliable answer comes from verifying the specific patient's benefits before the visit.
Carriers generally want proof of the prior active periodontal therapy, the SRP procedure codes and the dates they were performed, along with current periodontal charting showing the maintenance is warranted. For a patient who had their perio treatment at a previous office, that history usually has to be established with the carrier before the first maintenance claim will pay.
If the visit was a true maintenance visit with site-specific instrumentation, you still code it D4910, let the plan apply its alternate benefit at the prophy allowance, and bill the patient the difference. You can include a statement asking the carrier to apply the prophylaxis benefit if maintenance is denied. What you should not do is recode a genuine maintenance visit as a prophy to fit the plan, because that misrepresents the service.
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