# Influence of Cavity Geometry on the Fracture Strength of Dental Restorations: Finite Element Study
## 3 Results  
The linear analysis of both models completed all time steps of computation. In contrast, the onlay and inlay restorations' nonlinear simulations stopped at incremental steps 66 and 56, respectively, due to excessive deformation of the resin cement. Hence, step 56, corresponding to a 140 N load, was the basis for comparisons among CZM models, whereas for the comparisons among linear solutions of both models, the final time step was used instead. These comparisons were based on the qualitative interpretation of the band plots and quantitative analysis of stress values through different element groups at the same load step. The models' distribution of values was statistically analyzed using the one-way  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Body** & **Length (\(\mu\)m)** & **Refinement Zone (\(\mu\)m)** \\ \hline Cortical bone & 500 & - \\ \hline Cancellous bone & 500 & - \\ \hline Pulp & 500 & Dentin Region (100) \\ \hline Ceramic & 500 & Loading region (100) \\ \hline Enamel & 500 & Resin region (100) \\  & 500 & Dentin region (100) \\ \hline Dentin & 500 & Pulp region (100) \\  & 500 & Resin region (100) \\  & 500 & Bed region (50) \\ \hline Resin cement & 100 & Bed region (50) \\ \hline Loading body & 500 & Ceramic region (100) \\  & 500 & Resin region (100) \\  & 500 & Enamel region (100) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Length of the element edges attributed to each component and the refinement zones.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Compressive** & **Flexural Strength** & **Failure Strain (\%)** & **Shear Failure Strength (MPa)** & **GIC (N/m)** & **GIC (N/m)** \\ \hline
262 & 98 & 1.8 & 40 & 342 & 427 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mechanical properties of the resin cement adhesive [31,32].  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Material** & **Young’s Modulus (GPa)** & **Poisson’s Ratio** \\ \hline Cortical bone & 13.7 [33] & 0.30 \\ Cancellous bone & 1.37 [33,34] & 0.30 \\ Pulp & 0.002 [22,35] & 0.45 \\ IPS Empres CAD\({}^{\circledR}\) & 62 [19,36] & 0.30 \\ Enamel & 84.1 [35] & 0.2 \\ Dentin & 18.6 [35] & 0.31 \\ Loading body & 210 & 0.30 \\ Resin cement & 7.7 [31] \\ \hline \hline \end{tabular}
\end{table}
Table 3: Mechanical properties of all isotropic materials.  
ANOVA test of the Statistical Package for the Social Sciences (SPSS) version 23.0. Post hoc comparisons were made using a paired samples _t_-test and a significance level of 0.05.  
The inlay and onlay models revealed no significant difference between maximum values of the displacement magnitude, nor in their distribution pattern; the inlay restoration showed a maximum value of 47.4 \(\upmu\)m, while the onlay restorations showed a value of 48.0 \(\upmu\)m. These results can be seen in Figure 3, where the distribution of the displacement magnitude is presented for both ceramic restorations.  
The magnitude of the displacement for the remaining components of both restoration models had similar behavior and, therefore, no further comparisons related to the displacement are presented hereafter.