Cusp

A cusp is a raised, pointed or rounded eminence on the occlusal surface of a premolar or molar tooth, or on the incisal edge of a canine. Cusps are the primary functional elements of the posterior dentition, responsible for crushing, grinding, and shearing food during mastication. Premolars typically have two cusps (buccal and lingual), while molars have four or five cusps arranged in a pattern that varies by tooth type and arch position. The cusp tip, the ridge connecting cusps, and the fossa between cusps together form the occlusal anatomy that determines how opposing teeth interdigitate during function. Cusp morphology is a key consideration in restorative dentistry because any restoration must replicate the original anatomy to maintain proper occlusion and prevent bite disturbances.

Cusps are susceptible to fracture from traumatic occlusal forces, large existing restorations that undermine enamel, parafunctional habits such as bruxism, or thermal cycling of dissimilar restorative materials. A fractured cusp may present with symptoms ranging from sharp pain on biting to complete separation of a tooth segment. The clinical management of a cusp fracture depends on the extent of structural loss and whether the fracture extends below the gingival margin or involves the pulp. Minor cusp fractures can often be restored with direct composite or amalgam buildups, while more extensive fractures may require indirect restorations such as onlays or full-coverage crowns to protect the remaining tooth structure from further breakdown.

The status of the cusps directly influences the CDT code selection and associated reimbursement for restorative procedures. A restoration that replaces a cusp tip typically moves from a direct filling code into an onlay or crown code, which carries a significantly higher fee schedule allowance. Insurance carriers frequently request clinical documentation, including radiographs and photographs, to verify that cusp replacement was necessary before approving the higher-reimbursement code. Billing teams should ensure that the clinical record explicitly describes which cusps are involved, the extent of the fracture or decay, and the rationale for the selected restoration type. This documentation supports the claim and provides a defensible record in the event of a post-payment audit.