Most dental claim denials aren't about the dentistry. They come from a handful of preventable administrative gaps — the kind that slip through when a practice is busy and the billing process isn't airtight. Here are the seven we see most often, and what to do about each one.
1. Eligibility not verified
Coverage ended, the patient changed jobs and switched plans, or a dependent quietly aged out. The claim hits the payer and bounces back with remark code CO-4 or CO-27. Fix: verify every scheduled patient before the visit — not at check-in. Ideally 72 hours ahead so there's time to sort out surprises before the appointment.
2. Frequency limits exceeded
Most plans limit adult prophy (D1110) to two per benefit year and bitewings (D0274) to once per 12 months. Billed a day early, they'll deny. Fix: record frequency history during verification. Write the last date of service for every limited code into the patient's notes so whoever does the billing can see it without calling the payer.
3. Missing attachments
Crowns, build-ups, and perio scaling usually require radiographs, perio charts, or clinical photos to support medical necessity. Submitting without them guarantees a request for more information — or an outright denial with code CO-97. Fix: attach before submission, not after the denial. Build a checklist by procedure code so nothing slips through.
4. Coding errors
Wrong tooth number, incorrect surface notation, wrong quadrant on a scaling claim, or an outdated CDT code that was retired on January 1st. Each one is an immediate rejection. Fix: scrub every claim against the current CDT code set. The ADA updates codes every year — make sure your PMS fee schedule is updated within the first week of January.
5. Timely filing missed
Every payer has a filing deadline, and they vary widely — Delta Dental is typically 12 months from the date of service, while some plans are as short as 90 days. A claim that sits in a queue past that deadline loses all reimbursement permanently. Fix: submit within one business day of the encounter and track claim status weekly.
6. Coordination of benefits billed wrong
When a patient has primary and secondary insurance, the order matters. Bill the secondary first by mistake and you'll get a denial with remark code CO-22. Fix: confirm COB order during verification and document it in the patient's chart. When the primary pays, post the EOB and then bill secondary for the balance.
7. Missing clinical narratives
"Insufficient documentation" denials hit major procedures the hardest — posterior composites, full-mouth debridement, scaling in states of inflammation. The payer wants to know why the procedure was clinically necessary. Fix: attach a brief narrative (two or three sentences pulled from your clinical notes) when submitting procedures that are commonly flagged. It cuts these denials dramatically.