Investigation of thermal stress in different metal-ceramic restorations by mathematical analysis

Abstract

Objectives: The aim of this study was to investigate the effect of heat changes in oral environment producing thermal stresses (TS) in prosthetic restorations by a mathematical method. Material and Methods: Three different metals, commercial pure titanium (cpTi), precious metal alloy (Minigold, Bego dental, Bremen, Germany), chrome-cobalt-molybdenum (Wirobond, Bego dental, Bremen, Germany) were chosen for the frameworks. Titankeramik, VM13, and Omega 900 ceramics (Vita, Bad Sackingen, Germany) were used in theoretical analysis. The physical properties of the materials were obtained from manufacturers and from the literatures reports. The calculation method was based on Boley's equation. Results: In ceramics, the highest thermal stress was in titankeramik and the lowest was in VM13. Both commercial and theoretical samples were compared and at interface of the restoration, thermal stress accumulation was the highest in cpTi and titankeramik and the lowest was in precious metal alloy and VM13 respectively. In metallic frameworks CrCoMo had the highest and semiprecious metal alloy had the lowest thermal stress deposition in its structures. Conclusions: Thermal stresses are not capable of breaking the metal-ceramic bond strength but shorten the life span of the prosthetics.