Under what condition is a post and core typically recommended prior to crown placement?

A post and core is typically recommended before crown placement following root canal treatment because this procedure often results in the removal of a significant amount of tooth structure. After a tooth undergoes root canal therapy, it may become weakened and more prone to fracture due to the loss of structural integrity, particularly if the tooth has suffered extensive decay or is naturally slender.

The post is inserted into the remaining root canal space to provide additional support for the core material, which is then built up to create a stable foundation for the crown. This process restores the tooth's ability to withstand the biting forces it will encounter once the crown is in place.

In contrast, while crown fractures, severe decay, and gum disease may also necessitate crowns, they do not specifically require a post and core as a preparatory step unless root canal treatment has been performed. In cases of crown fracture or severe decay, the existing tooth structure might still be sufficient to support a crown without additional reinforcement, and gum disease typically focuses on periodontal treatment rather than endodontic considerations like post and core placement.