## 3 Results
### Transient Thermal Loads  
#### 3.2.1 Temperature Distribution  
In this section of the study for our simulations, four data points, A, B, C, and D on laminate veneer, enamel, dentin, and pulp were selected along the labio-palatinal (x-x) and the inciso-cervical (y-y) axes to represent the variations in temperature distributions in veneer restorations and tooth-supporting tissues for all design models (Figure 7). The results of the temperature distribution from the transient thermal analysis after exposure to 55 \({}^{\circ}\)C hot and 5 \({}^{\circ}\)C cold thermal loads are presented in Figures 8-10.  
The temperature distributions in the non-preparation design are shown in Figure 8. As a result of exposure to the 55 \({}^{\circ}\)C hot load, the temperature value at the initial contact section, point A, increased to 45.8 \({}^{\circ}\)C in the labio-palatinal and 47.6 \({}^{\circ}\)C in the inciso-cervical directions. The temperature values gradually decreased to 44.1 \({}^{\circ}\)C at point B, 42.6 \({}^{\circ}\)C at point C, and 40.3 \({}^{\circ}\)C at point D through the labio-palatinal axis. In contrast, the maximum temperatures through the inciso-cervical axis at points B, C, and D were found to be 44.6\({}^{\circ}\)C, 40.6 \({}^{\circ}\)C, and 39.5 \({}^{\circ}\)C, respectively. For the 5 \({}^{\circ}\)C cold load, a temperature decrease was observed at point A to 21.8 \({}^{\circ}\)C in the x-x direction and 14.8 \({}^{\circ}\)C in the y-y direction. In contrast, the minimum temperature through the labio-palatinal direction at points B, C, and D reached 28.8 \({}^{\circ}\)C, 29.6 \({}^{\circ}\)C, and 30.9 \({}^{\circ}\)C, respectively, while thermal values at the same points through the inciso-cervical direction were 19.1 \({}^{\circ}\)C, 26.7 \({}^{\circ}\)C, and 30.1 \({}^{\circ}\)C, respectively.  
Figure 6: von Mises stress distributions (MPa) in tooth structure. (**A**) Non-preparation design, (**B**) conventional preparation design, and (**C**) proposed preparation design.  
Figure 7: Calculated temperature change at the 4 points along both the x-x and y-y directions. (**a**) Veneer, (**b**) enamel, (**c**) dentin, and (**d**) pulp.  
observed at point A. These temperatures were found to be 24.1 \({}^{\circ}\)C, 25.3 \({}^{\circ}\)C, and 27.2 \({}^{\circ}\)C at points B, C, and D, respectively, through the x-x direction and to 17.0 \({}^{\circ}\)C, 21.4 \({}^{\circ}\)C, and 26.9 \({}^{\circ}\)C, respectively, at the same points through the y-y direction.  
Finally, the temperature changes in the proposed preparation design are shown in Figure 10. For hot loading, the maximum temperature was found to reach approximately 43.2 \({}^{\circ}\)C and 47.8 \({}^{\circ}\)C through the x-x and y-y directions on the outer ceramic point A. Along the inciso-cervical axis, these temperatures decreased to 40.2 \({}^{\circ}\)C for enamel at point B, 39.7 \({}^{\circ}\)C for dentin at point C, and 39.2 \({}^{\circ}\)C for pulp at point D, whereas temperatures of 44.8 \({}^{\circ}\)C for enamel, 42.8 \({}^{\circ}\)C for dentin, and 40.1 \({}^{\circ}\)C for pulp were obtained along the labio-palatinal axis. For cold loading, the restoration temperatures decreased to 24.08 \({}^{\circ}\)C and 17.96 \({}^{\circ}\)C at point A along the x-x and y-y directions, respectively. The thermal results at points B, C, and D were 27.7 \({}^{\circ}\)C, 28.7 \({}^{\circ}\)C, and 31.1 \({}^{\circ}\)C in the bucco-palatinal direction and 21.4 \({}^{\circ}\)C, 27.4 \({}^{\circ}\)C, and 31.2 \({}^{\circ}\)C in the inciso-cervical direction.