CDT Codes for Dental Billing: A Complete Guide for Dentists (2025)

Your CDT codes determine how much you get paid and whether a claim clears on the first try. Most general practices work from a few dozen codes on a regular basis, but getting even a handful of them consistently wrong adds up to thousands of dollars a year in downgrades and denials. This guide covers the codes that come up most in general dentistry: what each one means, when to use it, what your documentation needs to say, and the mistakes that turn a clean claim into a problem.

The exam codes: D0120 vs. D0150

D0120 (Periodic Oral Evaluation) is the routine recall exam that runs alongside a hygiene visit for an established patient. Most payers allow it twice a year. D0150 (Comprehensive Oral Evaluation) is the full diagnostic workup for a new patient, or for an established patient coming back after a long gap or a major health change. Most payers only allow it once per provider, per patient. Bill D0150 for a routine six-month recall and you're likely looking at a downgrade to D0120 reimbursement, or an outright denial pending records.

Preventive codes: prophylaxis and fluoride

D1110 (Prophylaxis, Adult) and D1120 (Prophylaxis, Child) cover routine cleanings and are almost universally capped at twice a calendar year across commercial and Medicaid dental plans. D1206 (Topical Fluoride Varnish) and D1208 (Topical Fluoride, Other) are usually covered for children, and increasingly for adults with documented caries risk, but a lot of adult plans exclude fluoride entirely or cap it at once a year. Verify before applying it chairside if a patient wants to avoid a surprise charge.

Restorative codes: amalgam and composite by surface count

Restorative fillings are billed by material and surface count, and surface count, not the tooth itself, is what determines the code. Getting the surface count wrong is one of the most common billing errors in general dentistry, and one of the easiest for a payer to catch against your submitted radiographs.

D2140/D2330: one surface (amalgam / resin composite)

D2140 covers a one-surface amalgam restoration; D2330 covers a one-surface resin composite restoration on an anterior tooth (D2391 is the posterior composite equivalent). These are the most frequently billed restorative codes in a general practice. Single-surface reimbursement typically runs $120 to $180 for amalgam and $130 to $200 for composite under commercial plans, with Medicaid fee schedules running well below that.

D2150/D2331: two surfaces

D2150 (amalgam) and D2331 (anterior composite) / D2392 (posterior composite) apply when the restoration involves two distinct surfaces of the same tooth. Make sure the chart note and radiograph clearly support two surfaces. Billing two when only one was restored is exactly the kind of documentation mismatch payers flag on review.

D2160/D2161 and D2332/D2393/D2394: three or more surfaces

D2160 (three-surface amalgam) and D2161 (four or more surfaces), along with their composite equivalents D2332, D2393, and D2394, cover more extensive restorations. Reimbursement scales with surface count, and the gap between a two-surface and three-surface claim can run $40 to $80. Surfaces need to be documented individually in the chart note, mesial, distal, occlusal, buccal, lingual, not just implied by the code you picked.

Tooth number, surface, and radiograph documentation

Because so many codes hinge on exact tooth number and surface, your chart note needs to record the universal tooth number, the specific surfaces treated, and, for anything beyond a simple restoration, a supporting radiograph or intraoral photo. "Filling, tooth #19" won't hold up on audit. "D2392, tooth #19, MO surfaces, pre-operative bitewing on file showing interproximal decay" will. That level of detail protects you against any code-mismatch challenge, and more payers are cross-checking submitted radiographs against billed surfaces before releasing payment than they used to.

Emergency and palliative codes: D0140 and D9110

D0140 (Limited Oral Evaluation, Problem Focused) covers a focused exam for a specific complaint, a toothache or a broken tooth, rather than a routine or comprehensive exam. D9110 (Palliative Treatment of Dental Pain) covers emergency treatment to relieve pain, like a pulp cap or a temporary restoration, when definitive treatment gets pushed to a later visit. Your documentation needs to establish the specific complaint and the palliative nature of what you did. Billing D9110 alongside a same-day definitive procedure on the same tooth is a common audit flag.

Sedation and anesthesia add-on codes: D9223 and D9243

General dentists and oral surgeons providing sedation alongside a procedure bill D9223 (Deep Sedation/General Anesthesia, each 15-minute increment) or D9243 (IV Moderate Conscious Sedation, each 15-minute increment) in addition to the procedure code. These bundle time-based anesthesia with the treatment performed on the same date of service. Hygienists and dental assistants can't bill these independently; they require a provider credentialed to administer sedation.

Periodontal codes

Periodontal treatment runs on its own set of CDT codes with their own frequency and documentation rules.

• ▸D4341, scaling and root planing, four or more teeth per quadrant. Needs periodontal charting that supports pocket depths consistent with active disease.
• ▸D4342, scaling and root planing, one to three teeth per quadrant. Same documentation standard, lower per-quadrant fee.
• ▸D4910, periodontal maintenance. The recall visit after active periodontal therapy. Most payers want D4341/D4342 or surgical periodontal treatment on file first.
• ▸D4355, full mouth debridement. Used when calculus buildup blocks a proper evaluation. Typically allowed once per lifetime per payer, so billing it repeatedly is a common audit trigger.

The mistakes that trigger downgrades and denials

Most billing issues in general practices come down to a short list of documentation mismatches. None of them require any intent to cause a compliance problem.

• ▸Surface-count mismatch: chart documents two surfaces, claim billed as three. The most common finding, and the easiest one to generate on a records request.
• ▸Comprehensive exam billed too often: repeating D0150 without a documented gap in care or a major health change raises flags at most payers.
• ▸Missing radiographs on major procedures: crowns, root canals, and extractions submitted without a supporting pre-op X-ray get denied pending records, routinely.
• ▸Missing tooth clause overlooked: billing a bridge or implant for a tooth that was already missing before the patient's coverage started, without checking the clause first.
• ▸Downgrade-eligible composite billed without a heads-up to the patient: some plans reimburse posterior composite at the amalgam rate, and patients should hear about the potential balance before treatment, not after the EOB shows up.

Keeping CDT codes, documentation, and payer-specific rules straight alongside a full patient schedule is a real burden. Logicware handles claim submission, coding review, and denial management for dental practices in Delaware and across the US. Contact us for a free billing audit to see where your current process has gaps.