When is a thermoplastic tray used to fabricate a custom provisional made?

A thermoplastic tray is used to fabricate a custom provisional after tooth preparation. This process typically takes place after the dentist has shaped the tooth to ensure the provisional accurately fits the prepared tooth and maintains the desired occlusion and aesthetics.

Fabricating the provisional before the tooth is prepared would not allow for the necessary adjustments that need to be made based on the specific contours and dimensions of the prepared tooth. Similarly, performing this step during the initial consultation or at the end of the procedure would not align with the workflow of dental treatment, as the temporary needs to be ready for placement immediately after preparation to provide protection and maintain function until a permanent restoration can be completed.