Biomechanical concerns with fixed partial dentures involving implants

Nine biomechanical factors involved in the design and fabrication of fixed partial dentures incorporating implants are discussed, focusing upon the deleterious effects of leverage, torsion, occlusal overload, and poor oral hygiene. Areas of concern are cantilevers, pier abutments, excessive fixed spans, use and misuse of nonrigid connectors, off-axis loading, occlusal plane to implant height ratio, inadequate support, distribution, and mandibular flexion and torsion.