## 4 Discussion  
The strengthening of acrylic denture base materials with different fiber reinforcements has been the subject of many investigations [2; 32; 4; 5; 7; 9; 10; 11; 14; 16; 17; 18; 20; 33]. In our study, it was noticed that the stresses in critical regions of maxillary dentures with different fiber reinforcements under concentrated occlusal load varied considerably with high-temperature changes. This issue is hardly mentioned in the literature  
For a long time, PMMA has been the most popular denture base material, despite the development of alternative materials to PMMA [9; 14]. PMMA is a material that has ease of manipulation, low cost, lightness, excellent aesthetic properties, low water absorption, and ease of repair. However, low thermal conductivity, drawbacks in mechanical strength, brittleness, a high thermal expansion coefficient, and a low elastic modulus are important features to be developed [14]. Acceleration in developments in composite technology has enabled materials to be reinforced with fiber materials [16]. Fiber reinforcements can increase the strength of the denture such as metal fillers, carbon fiber, nylon fiber, aramid fiber, and glass fiber. Fiber-reinforced denture bases frequently exhibit desired properties [14; 33]. As the strength of PMMA is poorer in tension than in compression, cracking of dentures is more likely to start from regions with a concentration of tensile stresses [7; 9; 34]. For the same reason, the strength of a denture in service is also affected by the presence of the incisal notch, which most likely provides the highest stress concentration [2]. [PERSON] and [PERSON] found that strain was increased at the incisal notch and that it was the prime \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Reinforcement Material of PMMA** & & & \\
**Denture and Value of Temperature** & & & \\ \hline CrCo 0\({}^{\circ}\) & 371.98 & \(-\)267.34 & 0.4895 \\ \hline CrCo 36 \({}^{\circ}\)C & 281.06 & \(-\)232.11 & 0.2852 \\ \hline CrCo 70 \({}^{\circ}\)C & 276.64 & \(-\)198.84 & 0.3409 \\ \hline UniCarbon/Epoxy 0 \({}^{\circ}\)C & 267.51 & \(-\)152.17 & 0.1599 \\ \hline UniCarbon/Epoxy 36 \({}^{\circ}\)C & 321.75 & \(-\)170.44 & 0.2359 \\ \hline UniCarbon/Epoxy 70 \({}^{\circ}\)C & 372.97 & \(-\)187.71 & 0.4693 \\ \hline UniGlass/Epoxy 0 \({}^{\circ}\)C & 140.53 & \(-\)63.77 & 0.5008 \\ \hline UniGlass/Epoxy 36 \({}^{\circ}\)C & 183.57 & -65.91 & 0.8991 \\ \hline UniGlass/Epoxy 70 \({}^{\circ}\)C & 224.21 & \(-\)67.92 & 1.4656 \\ \hline UniKevlar/Epoxy 0 \({}^{\circ}\)C & 119.14 & \(-\)99.67 & 0.1183 \\ \hline UniKevlar/Epoxy 36 \({}^{\circ}\)C & 271.21 & \(-\)106.86 & 0.2090 \\ \hline UniKevlar/Epoxy 70 \({}^{\circ}\)C & 339.26 & 113.65 & 0.3249 \\ \hline WovenCarbon/Epoxy 0 \({}^{\circ}\)C & 202.5 & \(-\)92.37 & 0.1071 \\ \hline WovenCarbon/Epoxy 36 \({}^{\circ}\)C & 238.75 & \(-\)103.65 & 0.1852 \\ \hline WovenCarbon/Epoxy 70 \({}^{\circ}\)C & 272.98 & \(-\)114.30 & 0.2902 \\ \hline WovenGlass/Epoxy 0 \({}^{\circ}\)C & 113.04 & \(-\)39.27 & 0.3437 \\ \hline WovenGlass/Epoxy 36 \({}^{\circ}\)C & 139.1 & \(-\)40.50 & 0.6937 \\ \hline WovenGlass/Epoxy 70 \({}^{\circ}\)C & 163.70 & \(-\)45.06 & 1.1504 \\ \hline WovenKevlar/Epoxy 0 \({}^{\circ}\)C & 125.98 & \(-\)45.14 & 0.4692 \\ \hline WovenKevlar/Epoxy 36 \({}^{\circ}\)C & 153.48 & \(-\)48.27 & 0.4260 \\ \hline WovenKevlar/Epoxy 70 \({}^{\circ}\)C & 179.44 & \(-\)59.42 & 0.7665 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Maximum and minimum stresses occurring in reinforcement materials and values of the Tsai-Wu strength ratio index. factor in contributing to the midline fracture of maxillary complete dentures [9]. [PERSON] pointed out that microcracks developed first in areas of stress concentrations where dentures are repeatedly flexed at a small load [2]. The strength of a denture diminishes as a crack propagates. When the maximum load of a cycle exceeds the remaining strength, catastrophic failure of the denture occurs. Many researchers have studied tensile stress distribution on the denture base.