The influence of the root cross-section on the stress distribution in teeth restored with a positive-locking post and core design: a finite element study

• Published in: Biomedizinische Technik Vol. 53; no. 5; pp. 255 - 258
• Main Authors: Schilling, Kai-Uwe, Rottner, Kurt, Boldt, Julian, Proff, Peter, Gredes, Tomasz, Richter, Ernst-Jürgen, Reicheneder, Claudia
• Format: Journal Article
• Language: English
• Published: Germany Walter de Gruyter 01.10.2008
• Subjects: Computer Simulation; Computer-Aided Design; Dental Stress Analysis; Equipment Failure Analysis; Finite Element Analysis; finite element method; Models, Theoretical; Orthodontic Appliance Design; positive locking; post and core restoration; Post and Core Technique - instrumentation; radicular dentin; Stress, Mechanical; tooth; Tooth - physiology; Tooth - surgery; Tooth Root - physiology; Tooth Root - surgery
• ISSN: 0013-5585; 1862-278X
• DOI: 10.1515/BMT.2008.037

Human teeth with substantial coronal defects are subject to reconstruction by means of post and core restorations. Typically, such a restoration comprises a slightly cylindrical post onto which an abutment of varying shape, depending on the designated restoration, is attached. As clinical results are not satisfactory to date, we proposed a new proprietary post and core design which makes use of positive locking. As this prefabricated system is not customised to an individual root's cross-sectional geometry (usually oval), a varying amount of radicular dentin is left in periphery of the core's outer edge. The aim of this study was to assess the implications of this fact, i.e., whether the root has to endure higher overall stress levels which ultimately may lead to failure of one of the components involved. A series of finite element simulations were performed to evaluate stress and strain on the system, in which the proposed post and core was embedded into a virtual dentin cylinder of different diameters, ranging from flush mounting of the restoration to a dentin excess of 4 mm, and subsequently loaded with forces with two angles of attack (90° and 130°). The results show that flush mounting yields an agreeable stress and strain distribution within the radicular dentin, but overall stress levels drop significantly with an excess of 0.5 mm of surrounding dentin. More than 1 mm excess was not found to have profound positive effects.