What type of undercuts should be applied for the retention of occlusal amalgam cavities in premolars?

For the retention of occlusal amalgam cavities in premolars, buccal and lingual undercuts are recommended. This choice is based on the anatomical structure and mechanics of retention in amalgam restorations.

In premolar teeth, the buccal and lingual surfaces provide greater surface area for bonding and retention. The presence of undercuts on these surfaces helps to mechanically lock the amalgam material in place, preventing it from dislodging during chewing forces. The design of the cavity is critical as it needs to ensure that the amalgam is securely held in position, and buccal and lingual undercuts facilitate this by creating mechanical retention that enhances the stability of the restoration.

It's important to note that while mesial and distal undercuts can also provide retention, the occlusal forces primarily act on the buccal and lingual sides. Additionally, occlusal undercuts would not be suitable here, as they do not conform to the necessary retention principles for the amalgam material being placed in the occlusal surface. Gingival undercuts may provide some level of retention but are not typically emphasized in occlusal cavity preparations for amalgam restorations.