Investigating the Stress Distribution Applied to Edentulous Ridge from Polyamide and Cobalt-Chrome Removable-Partial-Dentures using Three-Dimensional Finite-Element-Analysis

The objective of this study was to compare the Von-Mises-stress (VMS) distribution applied to the edentulous ridges from a Polyamide RPD (PRPD) with those from a Cobalt-Chrome RPD (CCRPD).

A patient with mandibular Kennedy Class I, Mod I was selected. The patientchr(chr('39')39chr('39'))s CBCT was cut off at 1 mm sections from the axial dimension. DICOM files were created. A three-dimensional-bone-model was prepared by segmenting the DICOM files and loading them in MIMICS software and the necessary modifications were applied on them using Geomagic software.The three-dimensional-designs were first developed using Exocad2016 CAD software. An extensive force equivalent to 150N was applied. Abaqus Software was used in order to meshing.  Then the stresses applied on the left and right sides of the edentulous ridges were measured.

In both models, the highest distribution of VMS in the edentulous ridges was observed exactly distal to the abutment teeth adjunct to the distal-extension-areas. In CCRPD, the mean stress on the left-edentulous-ridge was 220kPa and on the right-edentulous-ridge was 100kPa. In PARPD, the mean stress on the left-side-edentulous-ridge was 950kPa and on the right-side-edentulous-ridge was 600kPa. The amount of stresses on the edentulous ridges in the PARPD model (form 280Pa to 950PA) were too much less than those of CCRPD model (from 50kPa to 220kPa).

The polyamide bases can be flexed due to the applied forces and the forces can be distributed in them. So that PRPD can transfer very slight stresses to the underneath surfaces compared to CCRPD.