Three-dimensional finite element analysis of the retention of fixed partial dentures.

Four three-dimensional mathematical models were generated, each representing a three-unit fixed partial denture. The second premolar and second molar were used as abutments. Different associations of dental support preparation were tested. A 500-N axial load was applied to the pontic. Strains were analysed for each dental support by means of a three-dimensional finite element analysis technique. The results showed that the greatest strains were observed on the weaker abutment, the premolar. The cervical margin facing the edentulous area is affected most, regardless of the model or the dental support. The greater the dento-prosthetic differential surface between the two dental supports (thus the greater the retention differential) the higher the risk of unsealing.