## 4 Discussion  
In prosthodonics, the accuracy of the master cast used for the fabrication of fixed dental prostheses is paramount. The choice and proper manipulation of the final impression material are vital. According to the ADA specification on impression materials, there are specifications to test their accuracy and ability to reproduce fine details using simulated tooth models presenting areas that can be easily measured [21]. Therefore, a typodont master model with half-arch-prepared abutment teeth was used in the present study. Although variations exist among intra-oral scanners, this study utilized a TRIOS-3 3 Shape intra-oral scanner as a representative of the digital scanners used in fixed prosthodonics since it reportedly has the highest precision compared to other scanners [20]. The current study did not use the digital versions of the casts; instead, casts were printed to standardize the groups, to have the same testing conditions, and to avoid any errors, \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Pairwise Comparison** & **Mean (SD)** & **Mean Difference** & \(p\)**Value \({}^{*}\) \\ \hline \multirow{6}{*}{V} & ALG vs. AA & 4.06 (0.06) & \multirow{2}{*}{\(-\)0.05} & \multirow{2}{*}{0.02 \({}^{*}\)} \\  & ALG vs. A& 4.11 (0.02) & & \\ \cline{2-5}  & ALG vs. PVS-2 & 4.06 (0.06) & & \\ \cline{2-5}  & ALG vs. PVS-2 & 4.25 (0.02) & & \\ \cline{2-5}  & ALG vs. DIGITAL & 4.06 (0.06) & & \\ \cline{2-5}  & ALG vs. DIGITAL & 4.12 (0.02) & & \\ \cline{2-5}  & AA vs. PVS-2 & 4.11 (0.02) & & \\ \cline{2-5}  & AA vs. DIGITAL & 4.11 (0.02) & & \\ \cline{2-5}  & PVS-2 vs. DIGITAL & 4.12 (0.02) & & \\ \cline{2-5}  & PVS-2 vs. DIGITAL & 4.25 (0.02) & & \\ \hline \hline \end{tabular} \({}^{*}\) Indicates that the two means are significantly different according to [PERSON]’s HSD test. SD, standard deviation; ALG, alginate; AA, alginate alternative; HAPS, horizontal anteroposterior straight; HAPC, horizontal anteroposterior curved; HCA, horizontal cross-arch; V, vertical.  
\end{table} 
Table 4: _Cont._  
Figure 6: Percentage of deviation from the typodont master cast for impression materials and digital models. ALG, alginate; AA, alginate alternative; PVS-2, two-step putty–light body polyvinyl siloxane; HAPS, horizontal anteroposterior straight; HAPC, horizontal anteroposterior curved; HCA, horizontal cross-arch; V, vertical. while measurements were made using a stereomicroscope. The distance between the casts and microscope was standardized, and a ruler was used for calibration using the software. The discrepancies between stone casts and the master model had positive and negative values; to avoid false results due to the positive and negative values cancelling each other out, the data were converted to absolute values, which has been employed previously by other researchers [22,23]. The die stone casts obtained from PVS-2 presented the highest accuracy in the present study compared to the casts obtained from other impression materials and digital impressions. The best result in the present study was observed for the group using the putty-light body impression technique. This was supported by the findings of similar comparative studies [7,24,25]. This is because in the two-step putty-light body technique, there is uniform space for the light body material to polymerize with minimal shrinkage, and the details are recorded by the light body material only [7, 8, 9]. The 3D-printed models obtained from the intraoral scanning digital impression did not exhibit superior accuracy than the stone casts obtained from the conventional impression materials (ALG. AA, PWAD-2). This result was supported by the findings of [PERSON] and [PERSON], who found that the local deviations of the full-arch impressions were higher for digital impression systems than for conventional impression methods [26].