Cavity

A cavity is a structural defect or hole in a tooth that results from the progressive destruction of tooth hard tissues by the dental caries process. Cavities form when the demineralization of enamel by bacterial acids outpaces the natural remineralization provided by saliva and fluoride, leading to the collapse of the weakened enamel surface and the creation of a physical cavitation. Once the enamel is breached, the caries process accelerates through the softer dentin layer, which has a lower mineral content and larger tubular channels that support bacterial penetration toward the pulp. Cavities are classified by their location on the tooth using a system that identifies the involved surfaces, such as occlusal, mesial, distal, buccal, or lingual, and by their depth, ranging from incipient enamel lesions to deep cavities approaching or involving the pulp.

The treatment of cavities involves removing the decayed tooth structure using rotary instruments or air abrasion, preparing the remaining cavity walls to receive a restorative material, and placing a filling that restores the tooth to its original form and function. The choice of restorative material depends on the cavity size, location, aesthetic requirements, and patient preference, with composite resin and amalgam being the most commonly used direct restorative materials. For large cavities that compromise a significant portion of the tooth structure, indirect restorations such as onlays or full-coverage crowns may be indicated to provide adequate structural reinforcement. Untreated cavities continue to enlarge and deepen, eventually leading to pulp involvement, abscess formation, and potential tooth loss, which underscores the clinical importance of early detection and timely intervention.

Cavity treatment constitutes the largest volume of restorative procedures in most dental practices and generates a substantial portion of practice revenue. Each cavity restoration is coded using CDT codes that specify the tooth type, the restorative material, and the number of surfaces involved, with multi-surface restorations reimbursed at progressively higher rates. Billing accuracy depends on precise surface identification in the clinical chart, as each additional surface changes the procedure code and fee. Billing teams should audit charting practices to ensure that surface designations are documented before treatment begins and that the final restoration matches the surfaces indicated on the claim. Payers conduct post-payment audits comparing charted surfaces to radiographic evidence, and discrepancies between documented surfaces and radiographic findings are the most common reason for recoupment demands on restorative claims.