3D finite element analysis on esthetic indirect dental restorations under thermal and mechanical loading

Abstract

Thermo-mechanical finite element analyses in 3-D models are described for determination of the stress levels due to thermal and mechanical loads in a healthy and restored tooth. Transient thermo-mechanical analysis simulating the ingestion of cold and hot drinks was performed to determine the temperature distribution in the models of the teeth, followed by linear elastic stress analyses. The thermal loads were applied on the occlusal and lingual surfaces. Subsequently, coupled variation of the temperature and mastication loading was considered. The vertical loading was distributed at occlusal points, adding up to 180 N. Maximum stresses were verified in resin restoration under thermal loads. When studying coupled effect of mechanical loading with that arising from thermal effects, higher tensile stress values occurred in porcelain restorations, especially at the restoration-dentin interface. Regions of high tensile stress were detected and their possible clinical significance with respect to restoration damage and microleakage were discussed.

Heat Transfer and Thermal Stress Analysis of a Mandibular Molar Tooth Restored by Different Indirect Restorations Using a Three‐Dimensional Finite Element Method

“…Cold conditions caused tensile stress on the enamel and restoration surface, and compressive one in the dentin, whereas hot conditions caused compressive stress on the enamel and restoration surface, and tensile one in the dentin. These results are consistent with earlier studies …”

“…Lloyd et al reported that the magnitude of thermal stress in tooth, depending on ingestion of cold food and drink, is sufficient to cause cracks at enamel. In this study, the highest tensile stresses created by cold exposure (56 to 57 MPa) exceeded the ultimate tensile strength of enamel (10 MPa) . At 60°C condition, the highest compressive stresses (42 to 43 MPa) were lower than the ultimate compressive strength of enamel (262 MPa) .…”

“…These temperature values were within the range of described temperature extremes in the oral environment . For this study, the thermal exposure time period was 2 seconds, which indicates the hot and cold food and drink were maintained in the oral cavity for 2 seconds . Previous in vivo measurements demonstrated that the temperature changes on the buccal surface of teeth are low .…”

“…12,20,[23][24][25][26][27] The tooth was assumed to initially have a uniform temperature of 36ºC. To simulate the sudden intake of hot and cold food and drink, according to Cornacchia et al, 28 the temperature was assumed to change from 36 to 60 or 4ºC, respectively. These temperature values were within the range of described temperature extremes in the oral environment.…”

“…1 For this study, the thermal exposure time period was 2 seconds, which indicates the hot and cold food and drink were maintained in the oral cavity for 2 seconds. 28 Previous in vivo measurements demonstrated that the temperature changes on the buccal surface of teeth are low. 20 Thus, the occlusal and lingual surfaces of the tooth were assumed to be in contact with the hot and cold substances.…”