A photoelastic study of a split palatal major connector.

A study was made to determine if the split palatal design of maxillary major connectors used on distal-extension removable partial dentures would result in a reduction of torquing stresses on the abutment teeth when the bases were loaded. A photoelastic model to simulate the maxillary arch, abutment teeth with their periodontal ligaments, edentulous ridges, and mucoperiosteum of the palate and ridges was constructed. Two Kennedy Class II removable partial denture frameworks of chrome-nickel alloy were constructed to fit the photoelastic model. One framework had an intact palatal major connector, and the other had a split in the major connector to separate the base from the abutment tooth as a stress-breaker. The frameworks were placed on the model, loaded, and photographed with polarized light to record the stress pattern in the model. The results of this study showed that the split palatal major connector did reduce the stress delivered to the distal-extension abutment when the base was loaded on the experimental model. A significant amount of stress from loading of the framework was removed from the abutment tooth and transferred to the regions of the model underlying the base.