What is the primary situation for using laboratory-fabricated coverage?

The primary situation for using laboratory-fabricated coverage is when several teeth have been prepared. This is because laboratory-fabricated restorations, such as crowns or bridges, are designed to provide precise and customized coverage for multiple prepared teeth.

When several teeth are involved, laboratory fabrication allows for exact measurements, material selection, and aesthetic considerations that are tailored for the individual patient. These restorations are often more durable and have a higher level of precision compared to those made chairside, ensuring a better fit and function, which is crucial in cases where numerous teeth are treated at once.

In contrast, a single tooth restoration would more likely be done chairside using more immediate methods. Quick temporary solutions can serve as stopgap measures, but they are not the primary use case for laboratory fabrication. Lastly, while allergies to materials can affect the selection of materials used, it does not specifically pertain to the necessity of laboratory-fabricated coverage in the same way as multiple teeth being prepared.