Evaluation of the effects of connector type and prosthetic material on stress distribution in tooth-implant-supported fixed prostheses: A finite element analysis study

The aim of this study is to comparatively evaluate the effects of different connector types (rigid and non-rigid) and prosthetic superstructure materials (monolithic zirconia, metal-ceramic, PEEK-based composite, and zirconia-based composite) on stress distribution in implant, tooth, abutment, and bone structures within tooth-implant-supported fixed dental prosthesis systems using the finite element analysis (FEA) method. In this study, three-dimensional models of a fixed three-unit bridge supported by an implant in the second molar region and a natural tooth in the second premolar region were constructed. A total of twelve distinct models were created by varying the superstructure materials and connector types (rigid vs. non-rigid). Each model was analyzed under three different loading conditions: 550 N vertical force distributed over 11 cusp tips, 300 N oblique force applied buccally over 6 cusps, and 250 N oblique force applied lingually over 5 cusps. Von Mises stress values were separately assessed in the implant, tooth, abutment, and bone components. Among all models, those utilizing monolithic zirconia demonstrated the lowest stress values under all loading conditions. In contrast, the highest stress values—excluding the natural tooth—were observed in models with PEEK-based composite restorations. Metal-ceramic and zirconia-based composite materials exhibited comparable stress levels. Placement of the non-rigid connector mesial to the implant was found to optimize stress distribution, while distal placement resulted in increased stress concentrations on the implant. Furthermore, oblique forces applied from the buccal direction generated the highest levels of stress within the system. The combination of connector type and prosthetic material used in tooth-implant-supported fixed prostheses plays a decisive role in the biomechanical success of the system. Designs incorporating monolithic zirconia with a non-rigid connector positioned mesial to the implant appear to offer more favorable stress distribution. These findings highlight the importance of material selection and direction of occlusal force in the biomechanically sound design of tooth-implant-supported prostheses.