Three-dimensional printed models versus conventional stone models

Abstract

Aim: To compare the accuracy (trueness and precision)of cost-accessible three-dimensional (3D) printed models.Methods: A maxillary typodont (MM) was scanned andprinted 10 times in polylactic acid, resulting in 10 digitalmodels (DMs). Polyvinylsiloxane impressions were made toobtain 10 conventional stone models (SMs). All models werescanned and imported to CloudCompare software. The totalarea and three locations of interest were evaluated (zenith toincisal [Z-I], canine to canine [C-C], and first molar to canine[1M-C] distances). Total area evaluations were performed byaligning the MM and experimental models using the best-fitalgorithm and were compared using the Haussdorf distance.The distances between points of interest were measured usingthe point-picking tool at the same 3D coordinates. The meanvolumetric deviations were considered for trueness analysis.Precision was set as the standard deviation. Statisticaldifferences were evaluated using the Student’s t-test. Results:Total area volumetric comparisons showed that DMs showedsuperior trueness and precision (-0.02 ± 0.03) compared tothe SMs (0.37 ± 0.29) (P < 0.001). No differences between themodels were observed for Z-I (P = .155); however, SMs showedfewer deviations for C-C (P = .035) and 1M-C (P = .001) thanDMs. Conclusions: The DMs presented superior trueness andprecision for total area compared to the SMs; however, the SMswere more accurate when points of interest were evaluated.