When would an occlusal dental sealant typically not be applied?

The application of occlusal dental sealants is generally contraindicated when the tooth has decay. This is because sealants are designed to prevent decay by filling in the grooves and pits of the tooth surface, which helps to shield them from plaque buildup and acids. If a tooth is already decayed, applying a sealant would not address the existing issue and could potentially trap bacteria underneath the sealant, worsening the decay.

In contrast, scenarios such as tooth sensitivity, a too-smooth surface, or issues related to insurance coverage are not necessarily contraindications for sealant application. Tooth sensitivity might require addressing the underlying cause before any treatment, but it does not prevent the application of sealants in itself. A too-smooth surface may make it more difficult for the sealant to bond effectively, but it does not mean that sealants cannot be applied. Regarding insurance coverage, while it may influence a patient's decision to proceed with a treatment, it does not affect the clinical efficacy or rationale for using sealants when indicated.