A Comparison of Tooth Size and Arch Dimensions Among Measurements Taken Intraorally with 3D-Printed and Digital Models Obtained from Intraoral Scans

Background: To compare measurements of tooth size and arch dimensions among those taken directly intraorally with those made on digital and 3D printed models produced by intraoral scanning. Material and Methods: Sixty-six participants were recruited. Intraoral tooth size and arch measurements were taken intraorally with a digital caliper. Digital impressions were taken with an iTero® intraoral scanner. The three-dimensional digital models were measured using a 3D diagnostics tool (OrthoCAD software). The same digital models were used to fabricate physical models using a resin 3D printer (Elegoo Saturn). The measurements were repeated on 3D printed models by using the digital caliper. The recorded parameters included mesiodistal tooth widths, transverse, and antero-posterior dimensions. All measurements were repeated to assess intra- and inter- examiner reliability. The validity of each measurement method was assessed by repeated measures ANOVA with post-hoc pairwise comparisons (p<0.5). Results: The mean differences among three methods for all parameters were statistically significant (p<.05) but were considered to be clinically insignificant, except for the upper intercanine width. Direct intraoral measurements tend to be smaller than the digital and 3D printed models. The ICCs values indicated excellent intra- and inter-examiner reliability which demonstrates high reproducibility for all measurements on all model types. Conclusions: Direct intraoral measurements tend to be smaller than the digital and 3D printed models. However, the accuracy of measurements made directly intraorally, and on digital and 3D models from intraoral scans is clinically acceptable, except for the upper intercanine width.