Mechanics of tensile and shear stress generation in fixed partial denture retainers

Movements caused by the application of chewing loads to a fixed partial denture (FPD) are predictable. There are translational and rotational movements of the FPD and flexure of the structure. The location and magnitude of tensile and shear stresses affecting cement within retainers during mastication is related to the type of movement and determined by differences in mobility of abutments at each end of the FPD, length of span, and point of chewing load. The incidence of cement failure could be reduced with improved strategic stress resistance.