STRESS DISTRIBUTION OF MONOLITHIC AND VENEERED THREE-UNIT ZIRCONIA FDPS: A FINITE ELEMENT ANALYSIS.

Purpose: To evaluate the effect of restora0on design on fracture resistance and stress distribu0on of veneered and monolithic three-unit zirconia fixed par0al dentures (FDPs) using finite element analysis (FEA). Materials and Methods: Iden0cal epoxy resin replicas of mandibular second premolars and second molars (to serve as abutments for the three-unit bridges) were divided into four groups (n = 10): monolithic zirconia (MZ) restora0ons; conven0onal layering veneering technique (ZL); heat pressed-on technique (ZP); or CAD/CAM lithium-disilicate glass-ceramics (CAD-on). Specimens were subjected to compressive cyclic loading on the mesio-buccal cusp of the pon0c (load range 50 to 600 N; aqueous environment; 500,000 cycles) in a universal tes0ng machine. Data were sta0s0cally analyzed at 5% significance level with Fisher exact test and Kaplan-Meier survival analysis. 3D models were constructed in accordance with experimental groups. The stress distribu0on in each model was analyzed and evaluated according to the loca0on and magnitude of the maximum principal stresses (MPSs) using ANSYS so\ware. Results: Specimens from ZL and ZP groups failed at different stages of the 500,000 cycles fa0gue, while CAD-on and MZ restora0ons survived the fa0gue test. Sta0s0cally, there was a significant difference between the groups (P < .001). The MPS were located under the mesial connector in both monolithic and bilayered three-unit zirconia FDPs. These stresses were found to be higher in monolithic geometries compared to bilayered zirconia FDPs. Conclusions: Monolithic threeunit zirconia and CAD-on zirconia frameworks resulted in superior fracture resistance. Restora0on design significantly affected the stress distribu0on of three-unit zirconia FDPs. [ABSTRACT FROM AUTHOR]