Statement of problem: Connectors in fixed partial dentures (FPDs) are the weakest areas and responsible for failure in most cases. Optimizing the design of connectors will lead to higher strength and better performance of all-ceramic FPDs.
Purpose of study: The aim of this study was to use the finite element method in order to simulate the effect of connector width on stress distribution in all-ceramic FPDs.
Material and methods: Three 3-dimensional finite element models for a 3-unit FPD made of IPS-Empress 2 representing a lower first molar were created and a static load of 500 N was applied axially at mid pontic area. By choosing three different widths, 3 mm, 4 mm, 5 mm for connectors, three models I,II, and III for complete assembly of teeth and connectors were created.
Results: Maximum stress occurred in the connector area in all models. Compared to model I, stress decreased 24% in model III; so the wider connector lead to lower stress values.
Conclusion: Connectors are the most regular area for the fracture in all-ceramic FPDs because of high concentration of stress. Decreasing the width of connector raises the stress and increases the risk for fracture. Also, maximum stress in bridges is less than half of the strength of IPS-Empress2 and no failure is expected for all cases.
Clinical implications: This in vitro study of 3-unit all ceramicFPDs made with IPS-Empress2 shows that an increase in the width of connector reduces the stress concentration and improves the likelihood of long-term prognosis. Also, IPS-Empress2 can be used in posterior regions in many cases.