Load distribution on implants with a cantilevered substructure: an in vitro pilot study

The forces distributed on six Nobelpharma implants were analyzed by strain gauges fixed to various implant combinations that were placed in a replica of a human edentulous mandible and connected to a cast gold alloy superstructure. The mandible was supported on its lower border and the superstructure loaded in different locations. Although force distribution was found to be asymmetrical, statistical analysis revealed no significant differences. Loads applied to one side of the superstructure were largely carried by the implants on that side, demonstrating torquing of the casting in the midline. Loads applied to the cantilever resulted in large extension forces in implants on the opposite side of the fulcrum. The magnitudes of the loads distributed on the screw varied as a result of the combinations, inter-implant spaces, and implant locations.