Carol Tekavec, RDH
An inlay is an intracoronal (within the cusps of a tooth) restoration, fabricated from an impression, to correspond to the form of the prepared cavity. The restoration is then cemented or light-cured into the tooth. An inlay restores portions of a tooth that might also be restored using amalgam or composites.
An onlay is made and placed the same way, but its purpose is to also replace the cusp or cusps of a tooth. An onlay incorporates portions of a tooth (within the cusps of a tooth) that might correspond to areas commonly restored using amalgam, composites, or an inlay with the addition of a cusp or cusps.
Inlays usually are paid by insurance companies at the "Least Expensive Alternative Treatment (LEAT)" fee, frequently comparable to the fee for an amalgam. Depending on the cusp involvement, onlays may be a paid benefit - typically at a major benefit percentage (commonly 50 percent of the insurance-carrier`s fee schedule).
Insurers may require that two or more cusps of a tooth be involved or even all cusps be involved for the onlay to qualify as a paid benefit.
When inlays and onlays are recommended, a preauthorization may help the patient receive the best possible benefit. A preauthorization is not an insurance carrier`s promise to pay. It typically stipulates the probable benefit a patient may expect under prescribed circumstances, such as current eligibility and employee status. Patients always need to know that the total cost of treatment is their individual responsibility, regardless of insurance coverage.
The preauthorization request should contain a narrative explaining why an inlay or onlay is the best treatment, as well as an attachment of pertinent documentation. For example:
(1) "Vertical fracture lines are apparent on #30. The patient describes the tooth as painful." (Attach an intraoral photo.)
(2) "Tooth #31 has undermined cusps on MF, ML, and DL. Eighty percent of the cusp incline for these cusps is involved." (Attach an intraoral photo.)
If the tooth has sufficient decay, broken cusps, broken or defective restorations, or fractures where a crown would be a benefit, then usually an onlay also will be a benefit.
The ADA has revised its descriptions of resin and ceramic materials for inlays and onlays. The current ADA description for a resin inlay/onlay is: "Resin-based composite inlays/onlays must utilize indirect technique." Previously, the description stated, "Composite/resin inlays must be laboratory-processed."
For ceramic or porcelain inlays/onlays, the ADA description is: "Porcelain/ceramic inlays/onlays include all indirect ceramic, porcelain and polymer-reinforced, porcelain-type inlays/onlays." Previously, the description stated, "Porcelain/ceramic inlays presently include either all ceramic or porcelain inlays."
The ADA has provided us with several new codes describing 3/4 crowns. For a benefit to apply, a 3/4 crown usually must cover the entire occlusal surface and three of the four "sides" of a tooth. For example, #30 entire mesial surface, entire distal surface, and entire lingual surface, along with the occlusal surface, must need to be restored. A 3/4 crown and an onlay are not synonymous. Again, predetermining benefits for 3/4 crowns is recommended. Submit a radiograph and photograph, along with a narrative detailing problems such as decay, broken cusps, fractures and/or cracks.
When submitting for payment, keep in mind that all procedures involved with preparing the inlay, onlay, or 3/4 crown will be considered "inclusive" by the insurance carrier. Any fees for direct or indirect pulp-capping, liners, bases, and/or adhesives will not be paid separately by the carrier. For this reason, it is important to take into consideration all components and costs of each procedure performed as part of the inlay, onlay, or 3/4 crown before assigning an appropriate fee.
Carol Tekavec, RDH, is the author of a new insurance-coding manual, co-designer of a dental chart, and a national lecturer with the ADA Seminar Series. Contact her at (800) 548-2164 or at www.steppingstonetosuccess.com.
