## 4 Discussion
(2) Raising the pressure on the resin to the value of 11.65 bar raises the boiling/evaporating/monomer temperature to 193 \({}^{\circ}\)C, as well as raising the pressure on the resin to the value of 22.79 bar, which raises the boiling/evaporation/monomer temperature to 228 \({}^{\circ}\)C so that no porosity occurs within the acrylic resin, meaning that sufficient pressure led to an increase in the monomer'sboiling temperature and prevented it from evaporating [30]. (3) The cycle of coagulation or solidification (which is the temperature used to control coagulation at a specific time) is completely and automatically controlled by the autoclave device in the transition between the stages of vacuum, pressure raising and the introduction of high-temperature steam into the pressure chamber. Therefore, the cured acryl is not exposed to any effect of a random rise in temperature that leads to the boiling of the monomer and porosity at the base of the device [27]. (4) Studies have shown that it is possible to obtain satisfactory and convergent results between curing in a traditional water bath and other methods to provide the necessary heat to stimulate the fumigation reaction \"steam-dry air ovens-infrared rays... \" provided that the temperature and pressure applied to the crucibles are well controlled and non-random [29]. The close result in Groups 2 and 3, where no statistically significant differences appeared between them in terms of increase in the occlusal vertical dimension after curing, can be explained by the fact that despite Group 3 exposure to lower pressure and temperature than Group 2, the decrease in these conditions was increased by doubling the time from 10 min to 20 min in Group 3, resulting in two similar groups that were both clinically acceptable (<1 mm). Group 4 had statistically higher vertical occlusal dimension change compared to the other groups (\(p\) < 0.05). This may be explained by the fact that different parameters could play an important role in the change of the vertical occlusal dimensions, such as the pressure, temperature and curing time. The time of curing in G4 was 5 min which is half of the curing time in G2, as well as the pressure was 1.1 bar compared to 2.1 bar in G2, which demonstrated clinically accepted results. Therefore, time and pressure could be considered important parameters on the changes of the occlusal vertical dimension when using autoclave systems to harden the acrylic devices. The outcomes of the present study showed that two groups among the three autoclave curing groups (G2 and G3) are clinically acceptable for curing the bases of dentures. Therefore, these two methods (G2 and G3) could be used in dental practice to improve the physical and chemical properties of complete dentures as well as save time; and easier methods (fully automated) compared to the traditional method (G1). Within the limitations of an in vitro study, these results are relevant to confirm the complexity of the change in vertical occlusion dimension in the complete dentures. From a clinical standpoint, the difference observed in the vertical occlusal dimension after the different curing methods could indicate to the dental laboratories which use the autoclave technique to avoid the low pressure and the short time, which could influence the vertical occlusal dimension. One of the limitations of the present study was that the remounting of the models on the articulator is a very sensitive step and should be carefully performed. Moreover, the arrangement of artificial teeth should be carried out by an expert in order to validate the correct occlusion. Further studies are necessary to investigate denture-processing methods that can yield minimal vertical occlusal dimension change. Moreover, future studies should be performed to investigate the effect of autoclave curing on various resins, as well as the influences contributed by the different used times and temperatures of autoclave curing in the studies on different resins.