Mechanical behavior of major connectors--Part 1: Influence of supporting tissues

Mechanical properties of major connectors are crucial for the performance of prosthetics.

To determine the stiffness of systems of major connectors when supported by a model simulating the oral cavity.

Oral cavity models were made of plaster covered by resilient material. The stiffness of five maxillary and five mandibular major connectors were measured while loading vertically to the occlusal plane on two points, premolar or molar, directly on the frame work and when the major connectors were supported by the oral cavity model.

The mean stiffness values of the major connectors loaded on the oral models were 35-folds and 60-folds higher compared to non-supported results for the premolar and molar points, respectively, for both jaws. With no support, stiffness values when the major connectors were loaded on molar point were lower compared to premolar point. When major connectors were supported by the oral models, the opposite occurred: the system showed higher stiffness when the major connectors were loaded on the molar point compared to premolar point.

The influence of supporting tissues on the stiffness of major connector systems should be included in further studies.

It is recommended to end the distal portion of the dentures at the second molar and to use the whole support provided by the oral tissues of the ridge.