Effect of splinting on load distribution of extracoronal attachment with distal extension prosthesis in vitro

Previous reports have suggested that the restoration of distal extension edentulous areas with an extracoronal precision attachment partial denture necessitates splinting of abutments. However, the number of splinted teeth remains controversial. In this study, strain gauge technology was used to monitor stresses induced around the abutment and in the distal extension area under different loads as a function of the number of splinted abutments. Three strain gauges were installed in the outer buccal, lingual, and distal surfaces of the abutment to record stresses in the three planes of motion, and another gauge was placed under the distal extension base. The reduction of the number of splinted units from three to two resulted in an insignificant increase of stresses recorded, whereas reduction of the number from two to one resulted in a significant increase of stresses nine times greater than the three-unit splint values. On the basis of this in vitro model, at least two teeth on each side should be splinted when extracoronal distal extension attachment prostheses are used.