Accuracy and reproducibility of permanent dentitions and dental arch measurements: comparing three different digital models with a plaster study cast

Aim: The objective of the present study was to assess the accuracy and reproducibility of permanent dentition and dental arch measurements of three digital scanners compared with the gold standard, a physical plaster cast.
Materials and methods: In this cross-sectional study, the following records of 30 patients were used: 1) orthodontic physical plaster study cast (PPSC); 2) digitally scanned physical model (DSPM), 3) direct intraoral model scanned with a Trios color scanner; and 4) direct 3D CBCT digital model. The following 3D measurements were obtained: mesiodistal tooth dimensions; total tooth materials; dental arch perimeters; total arch lengths; and intermolar, interpremolar, and intercanine widths. The measurements on the three digital models were contrasted with those on the PPSC. Differences were tested using a dependent t test for intragroup comparisons. A P value of < 0.05 was considered statistically significant. Intraclass correlation coefficient was used to assess intra- and interexaminer reliability.
Results: Except for the mesiodistal dimensions of the mandibular left central incisors (P < 0.001) and the mandibular intercanine width (P = 0.041), no statistically significant differences were found between the measurements made directly on the PPSC and those on the three digital models. The mean discrepancies between the methods ranged from as low as 0.003 mm to as high as 0.67 mm for the total tooth materials, and as low as 0.01 mm to as high as 0.37 mm for the total arch length. For the transverse dimension, the mean discrepancies ranged from as low as 0.3 mm for the maxillary intercanine width to as high as 0.5 mm for the mandibular intercanine width. However, these significant differences were not considered clinically significant.
Conclusions: The DSPM, Trios color scanner digital model, and direct 3D CBCT digital model appear to be adequate, reliable, and time-saving alternatives to the PPSC when analyzed using a digital caliper.