## 3 Results  
All groups showed a statistically significant increase in the vertical occlusal dimension after the polymerization step compared to the initial situation (_p_ < 0.05).  
The lowest change between the initial dimension and the change after polymerization step was observed in G1 (0.703 \(\pm\) 0.078 mm).  
The greatest change between the initial dimension and the change after polymerization step was observed in G4 (1.263 \(\pm\) 0.063 mm).  
Moreover, G2 (0.844 \(\pm\) 0.061 mm) and G3 (0.88 \(\pm\) 0.059 mm) demonstrated a statistically significant increase in the vertical dimension between the initial measurement (before polymerization) and the final measurement (after polymerization) (_p_ < 0.05).  
Statistically significant lower vertical dimension changes were detected in G1 compared to the other groups \"G2, G3, G4\" (_p_ < 0.05).  
Statistically significant higher changes were detected in G4 compared to the other groups \"G1, G2, G3\" (_p_ < 0.05).  
No statistically significant differences were found between G2 (0.844 \(\pm\) 0.061 mm) and G3 (0.88 \(\pm\) 0.059 mm) (_p_ > 0.05) (Table 1).  
G1, G2 and G3 demonstrated vertical occlusal dimension changes of complete acrylic dentures lower than 1 mm after the different curing techniques, whilst G4 demonstrated dimension changes more than 1 mm after the polymerization step \"(121 \({}^{\circ}\)C/1.1 bar) for 5 min\".  
The change in the occlusal vertical dimension of the complete dentures was studied previously for different curing techniques such as compression method [18], injection modeling [19] and microwave processing [20; 21]. [PERSON] et al. [20] determined the influence of different curing cycles in a microwave oven on changes in the occlusal vertical dimension of complete dentures. They reported that microwaves could change the vertical occlusal dimension (<0.5 mm). Moreover, [PERSON] et al. [21] also studied the influence of curing in a microwave on the occlusal vertical dimension of complete dentures. They showed that the use of microwaves could increase the vertical occlusal dimension (0.628 \(\pm\) 0.128 mm). [PERSON] et al. [19] demonstrated that the injection method with different parameters could influence the vertical occlusal dimension of complete dentures between 0.52 and 0.75 mm. [PERSON] [18] compared the changes in vertical dimension after injection or compression  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **G1** & **G2** & **G3** & **G4** & **Statistical Analysis** \\  & & & & & **(_p_ < 0.001) “Tukey’s Test”** \\ \hline Before polymerization (mm) & 127.391 \(\pm\) 0.048 & 127.476 \(\pm\) 0.026 & 127.341 \(\pm\) 0.021 & 127.328 \(\pm\) 0.032 & \\ After polymerization (mm) & 128.094 \(\pm\) 0.094 & 128.320 \(\pm\) 0.074 & 128.221 \(\pm\) 0.074 & 128.591 \(\pm\) 0.061 & \\ Difference (mm) & 0.703 \(\pm\) 0.078 & 0.844 \(\pm\) 0.061 & 0.88 \(\pm\) 0.059 & 1.263 \(\pm\) 0.063 & G1 \(<\) G2, 3, 4 \\  & & & & & G4 \(>\) G1, 2, 3 \\ \hline Statistical analysis “paired _t_-test” & \(p\) < 0.001 & \(p\) < 0.001 & \(p\) < 0.001 & \(p\) < 0.001 & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Mean and standard deviations of the vertical occlusal dimension values before and after polymerization.  
procedure. The study showed that the injection method had lower changes (0.02 mm) compared to the compression procedure (0.66 mm).