Accuracy of Master Casts Generated Using Conventional and Digital Impression Modalities: Part 2—The Full Arch Dimension

The aim of this study was to evaluate the accuracy of master casts generated by conventional (putty and light body consistencies polyvinyl siloxane and alginate) and digital impression techniques on a typodont master model with full-arch-prepared abutment teeth. The null hypotheses tested were as follows: (1) no statistically significant differences in accuracy between casts made by the two impression modalities and the typodont master model at each of the four locations (horizontal straight, horizontal curved, horizontal cross arch, and vertical), and (2) no statistically significant differences in dimensions measured at each of the four locations between the casts generated using the conventional and digital impression techniques. For the conventional technique, 10 impressions each were made for the typodont model using polyvinyl siloxane and alginate impression materials, and the casts were poured. For the digital technique, the typodont model was scanned 10 times using a TRIOS-3 3Shape intraoral scanner, and the casts were printed. The measurements for the horizontal (anteroposterior and cross arch) and vertical dimensions were made using a stereomicroscope and the accuracy of fabricated casts was expressed as the percentage of deviation from the typodont master model’s values. A one-way ANOVA and Tukey’s test (p < 0.05) were used to analyze the data. In the current study, the only measurement that did not exceed 0.5% in dimensional change was with the stone casts produced by both the 3M ESPE PVS and Kromopan alginate impression materials at the HAPC dimension. The casts generated by impressions made using the 3M ESPE PVS impression material were the most accurate, whereas the casts generated by making digital impressions using the TRIOS-3 3Shape intraoral scanner were the least accurate among the three tested groups. The greatest number of distortions above 0.5% (at all dimensional locations) was produced by the digital models printed using the ASIGA 3D printer.