Comparative Study of Stress Distribution in Upper Incisors. Biomimetic Behavior of Post System

Objective: This work proposes a study about the distribution of mechanical stresses in the radicular dentin of restored with different posts systems, by means of the Photoelastic and the Finite Element Techniques. This analysis is conducted for the following posts systems: carbon fiber, fiberglass, zirconium, stainless steel, titanium and cast metal (Cu-Al alloy) and the healthy tooth (control). The computer analysis and numerical results were validated by laboratory experimental data (Phoelastic). Methods: For this purpose, representative two-dimensional models of the central upper incisor are built for both methods. These models are subject to a 100N load applied at the tip of the crown, at 45° from the axle along the tooth. The results are expressed in terms of the Von Mises and Sy stresses and the fringe order, for the finite element and photoelastic methods, respectively. Results: Through the analysis of these results, it can be concluded that significant stress distribution differences arise between the six different pin systems tested, so that those made of zirconium, stainless steel, titanium and cast metal produced high stress concentration at the post/dentin interface region. In the cases of the carbon fiber and fiberglass pins, on the other hand, the stress distribution along the radicular surface is uniform, lacking stress concentration areas. Conclusion: The zirconium, stainless steel, titanium and cast metal pins present mechanical properties which are different from those of the tooth structure, resulting in significant alterations over the mechanical behavior of the dental structure. The non-metallic pins comply more satisfactorily with the requirements necessary to provide a mechancial behavior more similar to that of the dental structure, the compatibility among the mechanical properties found in these systems and the dentin providing a biomimetic behavior, reducing the risk of failure or fracture of the root fractures. FAPESP (00/0633-1)