This study evaluates stresses induced on the supporting area when using three different coping materials (zirconia, metal and PEEK) on prepared canines supporting lower complete overdentures. The different coping materials—zirconia, metal, and PEEK—were investigated with the goal of assessing the strains placed on the supporting area. Three casts made of epoxy resin were created to depict fully edentulous lower arches, with the exception of the left and right canines. Simulation of periodontal ligaments and alveolar mucosa rubber was done. A zirconia post and coping were built on both canines for the first cast; a nickel-chromium alloy was used for the second cast; and polyetheretherketone (PEEK) was used for the third cast. Use of four strain gauges fixed on the crest of the ridge, loading machine and strain meter were done to evaluate the stresses imposed on the supporting areas and compare the three different materials.
The three different types of coping materials differed significantly from one another. PEEK material had the highest value of stresses on the supporting ridge area, followed by zirconia, and metal copings had the lowest values. This can be explained by the fact that metal (Ni-Cr) has high mechanical properties regarding rigidity and hardness while zirconia coping cracks with loading, followed by expansion and sealing, which reduces stress on abutment teeth and concentrates stress on the alveolar ridge. With regard to PEEK copings, a high modulus of elasticity produced a stress-breaking effect that minimized strains on the abutments and increased stresses on the remaining alveolar ridge.