In the construction of an onlay, where should the heavier bevel be placed?

The placement of the heavier bevel in the construction of an onlay is critical for ensuring optimal fit and function. The correct answer points to the functional (working) cusp, which is essential because this is the area that will experience the greatest forces during chewing and other occlusal activities.

By placing the heavier bevel on the functional cusp, the design enhances the adaptation of the onlay to the existing tooth structure, facilitating better resistance to cuspal fracture and minimizing the risk of failure. The bevel reduces the internal angles, allowing for a more favorable stress distribution when occlusal forces are applied. This strategic placement also aids in the retention of the onlay, promoting a secure bond with the tooth and improving overall durability.

Alternative locations for the bevel, such as on the mesial or distal cusp, would not provide the same level of functional advantage since these areas do not bear as much load in typical occlusion scenarios. Similarly, placing a heavier bevel on the non-functional cusp could potentially lead to unnecessary weakening of that area, which is less effective for retention and could compromise the integrity of the restoration.