What distinguishes functional cusp reduction from nonfunctional cusp reduction for PFM?

The distinction between functional cusp reduction and nonfunctional cusp reduction primarily lies in their specific requirements in terms of tooth preparation for porcelain-fused-to-metal (PFM) restorations. Functional cusp reduction, which pertains to the functional cusps involved in occlusal contacts during chewing, usually requires additional beveling. This beveling is essential for providing a more favorable blending of the porcelain with the metal framework, thus enhancing the aesthetics and function of the restoration. The functional cusps bear more load during mastication, necessitating careful design to ensure adequate strength and durability while maintaining the proper occlusal contour.

In contrast, nonfunctional cusp reduction does not typically call for this additional bevel, as these cusps do not participate in occlusion during functional movements. The approach to these cusps may be more straightforward since the aesthetic and functional demands differ from those of functional cusps.

Understanding these distinctions is crucial for effective prosthetic design, ensuring that the restoration not only fits well but also performs optimally under the forces of mastication.