الفهرس 
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Abstract
The present study was performed to investigate the influence of different connector designs on the fracture resistance and stress distribution on Incoris TZI fixed partial dentures (fractographic and FEM analyses).
Two designs were constructed according to the radius of curvature at the occlusal embrasure (OE) and gingival embrasure (GE).
• Design (I) OE 0.90mm GE 0.25mm.
• Design (II) OE 0.25mm GE 0.90mm.
For the laboratory part of the study, a stainless steel master model was machined to simulate a mandibular second premolar, and second molar prepared as an abutments for missing mandibular first molar, from which 12 epoxy resin models were reproduced. The twelve epoxy models were randomly allocated into two equal groups (A and B). Each group received six standardized zirconia all-ceramic FPDs. Twelve Incoris-TZI Zirconia FPDs were milled using Cerec Mc XL CAD-CAM machine system. The morphology and the thickness of the entire test FPDs were standardized by the use of CAD/CAM system. All FPDs were adhesively luted on epoxy resin models with dual cure resin cement (Multilink Cement system) following the manufacturer instructions.
Subsequently, the zirconium FPDs were subjected to thermal and cyclic load to stimulate the clinical condition, corresponding to 6 months of clinical service. Then loaded was applied until fracture using universal testing machine to indicate the fracture resistance for each zirconia FPDs. The load at which fracture had occurred was viewed in Newton’s on a reading monitor.
After recording the reading from the monitor, the fractured FPD were inspected and visually examined to determine the fracture mode of each sample.
Two three dimensional finite element models (FEMs), representing two FPD connector designs, were created and analyzed. Descriptive statistics were calculated for each group, which include mean, standard deviation, minimum and maximum values. Results of fracture resistance and stress analysis were analyzed using student t-test.
The results showed a good correlation between the experimentally measured failure loads and those predicted by FEM simulation analyses.