Distribution of occlusal forces along unilateral posterior two-unit cantilever segments in cross-arch fixed partial dentures

Abstract

Axially directed occlusal forces over unilateral posterior two-unit cantilever segments of cross-arch fixed partial dentures were measured during natural functioning by using built-in transducers, one in each cantilever unit. The mean local maximal occluding and maximal chewing forces were significantly larger over the first (124 N and 64 N) than over the second (21 N and 29 N) cantilever unit. The average intraindividual ratio between the forces over the first and second cantilever unit amounted to 12:1 for maximal occlusion and 3:1 for maximal chewing. Despite the smaller mean total maximal chewing (92 N) than mean total maximal occluding cantilever force (145 N), the resulting axially directed mean bending moments in the joint between the distal abutment crown and the cantilever segment did not differ significantly. This is explained by the larger mean maximal chewing (29 N) than mean maximal occluding (21 N) force over the second cantilever unit. This demonstrated that not only the magnitude of occluding and chewing forces over cantilever segments but also their distribution along the cantilevers is of importance for the magnitude of functional stress created in cantilever fixed prosthesis.