Thermoelastic Analysis of Post–Restored Teeth Using a Generalized Mathematical Approach

نویسندگانحسین اشرفی,محمد شرعیات
همایش1st MEFOMP International Conference of Medical Physics
تاریخ برگزاری همایش۲۰۱۱-۱۰-۲۶
محل برگزاری همایششیراز
سطح همایشبین المللی
چکیده مقالهBoth tissue losses and missing teeth can affect the biomechanical equilibrium of the chewing system in a negative way. Thus the prophylactic restoration of these shortcomings is required. Many different materials can be used in restorative and prophylactic treatments. Metallic, ceramic and composite based filling are used in the restoration. In addition, the implant materials located in the jaw are selected of different kinds. Thermal stresses can be made in the restorations of teeth by heat changes. Thermal stress distribution in such a system is dependent on the geometry, rigidity and material. Because of different physical and thermal properties of different materials in a post-restored tooth, hot and cold liquid in the mouth can create temperature gradients in a tooth and these changes can cause different thermal stress. These thermal stresses can become higher than before in the vicinity of the interfacial contact areas between different materials. Thermal stresses can be also combined with mechanical ones, which they can cause the microscopic fractures in the dental structures. In this study, the constitutive relations of thermo-elasticity are rigorously formulated, and a generalized finite element formulation is derived. Due to second law of thermodynamics, a nonlinear term, which appears in both the energy equation and the Clausius-Duhem inequality, is incorporated in the finite element formulation. A MATLAB computer program was developed for this formulation. Tooth was assumed anisotropic, homogenous, elastic and symmetrical. Temperature changes on the restored tooth were calculated and then thermal stresses as a result of temperature changes were carried out. Post, core and crown material have a significant effect on concentrations of thermal stresses. It has been found that minimum stresses are found at the interfaces when Ti–Ti alloy is used as post material and crown material.