Coding inlays, onlays, and crowns

Coding for inlays and onlays always has been somewhat confusing. By definition, an inlay is an intracoronal restoration made outside the mouth to correspond to the form of the prepared cavity. It is then cemented or light-cured into the tooth.

Carol Tekavec, RDH

Coding for inlays and onlays always has been somewhat confusing. By definition, an inlay is an intracoronal restoration made outside the mouth to correspond to the form of the prepared cavity. It is then cemented or light-cured into the tooth.

An onlay is a restoration made outside the mouth that replaces a cusp or cusps of the tooth. It also is cemented or light-cured onto the tooth. Inlays and onlays usually are paid at the least expensive reimbursable fee, frequently comparable to the fee for an amalgam.

When inlays and onlays are recommended, a pre-authorization may help the patient receive the best possible benefit. The pre-authorization should contain a narrative giving the reasons an inlay or onlay is the best treatment. Reasons might include:

1. A patient`s documented allergy to mercury, with allergy test results attached.

2. Beginning vertical fracture lines on the tooth involved. (An intraoral photograph can be helpful).

3. Periodontal conditions where supragingival margins are desired for optimal periodontal health.

4. Documented blood studies that indicate a detrimental percentage of mercury in the patient`s blood.

5. Undermined cusp(s). (Attach an intraoral photograph.)

6. An explanation that an inlay/-onlay procedure is preferred to restore functional strength while preserving sound tooth structure.

While ADA codes for crowns include separate listings depending on what type of metal or material is used, no distinction is made for the type of metal used in the following inlay codes: 02510-Inlay, metallic, one surface; 02520-Inlay, metallic, two surfaces; 02530-Inlay, metallic, three or more surfaces; 02543-Onlay, metallic, three surfaces; and 02544-Onlay, metallic, four or more surfaces.

All ceramic and porcelain inlays and onlays are coded as follows: 02610- Inlay, porcelain/ceramic, one surface; 02620-Inlay, porcelain/ceramic, two surfaces; 02630-Inlay, porcelain/cer-amic, three or more surfaces; 02642- Onlay, porcelain/ceramic, two surfaces; 02643-Onlay, porcelain/ceramic, three surfaces; 02644-Onlay, porcelain/cera-mic, four or more surfaces.

Lab-processed composite and/or resin inlays and onlays may be coded: 02650-Inlay, composite/resin, one surface; 02651-Inlay, composite/resin, two surfaces; 02652-Inlay, composite/ resin, three or more surfaces; 02662-Onlay, composite/resin, two surfaces; 02663-Onlay, composite/re-sin, three surfaces; and 02664-Onlay, composite/resin, four or more surfaces.

Inlays and onlays made from newer materials not completely described by any current codes should be coded by using the code and description that most closely fits the material. If the material being used requires a more complicated technique or higher laboratory costs, a narrative can be included describing the technique and the reason for the fee.

Code 02999-Unspecified Restorative Procedure, By Report, may also be used when no other ADA code accurately describes the technique or material. The "99" codes often prompt a review by an insurance dental consultant, which may delay payment, but may increase the benefit amount paid. New codes will be made available in the year 2000, when the new CDT-3 code book is published.

Alloys used in crowns are defined on the basis of the percentage of noble metal they contain. High noble must contain 60 percent or more of gold, palladium, or platinum, with at least 40 percent of the metal being gold. Noble must contain 25 percent of gold, palladium, or platinum. Base metal contains less than 25 percent of gold, palladium, or platinum. Crowns made with "porcelain fused to metal" or "all metal" are common in many dental offices. Most insurance carriers reimburse patients for anterior or bicuspid "porcelain-fused-to-metal" crowns with no "downcoding" (substituting a lesser-paid code) or "downgrading" (substituting a base metal for a noble one). Molar teeth may be considered ineligible for "porcelain-fused-to metal" crowns if the patient`s insurance contract specifies that no aesthetic procedures are covered.

Defective crowns usually must have been in place for over five years to be eligible for reimbursement by most plans. Include the date of the original crown placement with the reason a new crown is needed on the claim form.

Carol Tekavec, RDH, is the author of two insurance-coding manuals, co-designer of a dental chart and a national lecturer. Contact her at (800) 548-2164 or at www.steppingstonetosuccess.com.

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