Temperature and Thermal Stress Distributions in Onlay Restored Teeth Utilizing Finite Element Analysis

This study is performed to investigate the distribution of temperature and thermal stresses in ceramic and gold onlay restorations using 3D finite element analysis.

A three-dimensional model of mandibular first molar is created using 3D scanning method. The simulated model is consisted of enamel, dentin, resin cement and onlay restoration (made of type 2 gold alloy or lithium di-silicate ceramic). The crown of the tooth is subjected to temperature changes (4°C or 60°C) for 2 seconds and the temperature distribution and also resultant stresses in the tooth are analyzed.

The pattern of temperature and stress distribution is the same in both restorations but heat transfer from the surface to the depth of the tooth in gold restoration is more than ceramic restoration. The maximum stresses in all parts (enamel, dentin, cement and onlay), in ceramic restoration are higher than gold restoration.In both restorations, the stress at the gingival contact surface of the cavity is higher than the other parts of restoration. The maximum stress is detected in the enamel. Moreover, thermal stress in the cervical area of dentin is higher than other parts of dentin.

According to the findings of this research, ceramic onlay (which shows better heat isolation) is proposed for deep restorations while due to lower thermal stress in gold onlay, it is more efficient for restorations with shallow depth cavities.