Validity, reliability, and reproducibility of the iOC intraoral scanner: A comparison of tooth widths and Bolton ratios

Abstract

The objectives of this study were to determine the validity, reliability, and reproducibility of the iOC intraoral scanner (Cadent, Carlstadt, NJ) and its associated OrthoCAD software (Cadent) in measuring tooth widths and deriving Bolton ratios. Thirty subjects had impressions taken of their teeth and rendered as stone casts. In addition, their mouths were scanned with the iOC and the scans were converted into digital models. Tooth widths were measured with a digital caliper from the physical models and with the OrthoCAD software from the virtual models. Bolton ratios were derived using the data from each method. Validity was assessed with a paired t test, reliability with the Pearson correlation coefficient, and reproducibility with the intraclass correlation coefficient. Although there were statistically significant differences between mean tooth widths (P=0.0083) and Bolton ratios (P= 0.0354 and P<0.0001) with the 2 methods, the discrepancies were deemed to be clinically insignificant. The Pearson r for tooth-width replications was 0.99 for both techniques, and all intraclass correlation coefficient values exceeded 87%. The iOC/OrthoCAD system can be used to measure tooth widths and calculate Bolton ratios with clinically acceptable accuracy and excellent reliability and reproducibility. It appears to be a sound orthodontic aid.