Accuracy and reproducibility of measurements on plaster models and digital models created using an intraoral scanner

The purpose of the present study was to evaluate the accuracy and reproducibility of measurements made on digital models created using an intraoral color scanner compared to measurements on dental plaster models.

This study included impressions of 28 volunteers. Alginate impressions were used to make plaster models, and each volunteers' dentition was scanned with a TRIOS Color intraoral scanner. Two examiners performed measurements on the plaster models using a digital caliper and measured the digital models using Ortho Analyzer software. The examiners measured 52 distances, including tooth diameter and height, overjet, overbite, intercanine and intermolar distances, and the sagittal relationship. The paired t test was used to assess intra-examiner performance and measurement accuracy of the two examiners for both plaster and digital models. The level of clinically relevant differences between the measurements according to the threshold used was evaluated and a formula was applied to calculate the chance of finding clinically relevant errors on measurements on plaster and digital models.

For several parameters, statistically significant differences were found between the measurements on the two different models. However, most of these discrepancies were not considered clinically significant. The measurement of the crown height of upper central incisors had the highest measurement error for both examiners. Based on the interexaminer performance, reproducibility of the measurements was poor for some of the parameters.

Overall, our findings showed that most of the measurements on digital models created using the TRIOS Color scanner and measured with Ortho Analyzer software had a clinically acceptable accuracy compared to the same measurements made with a caliper on plaster models, but the measuring method can affect the reproducibility of the measurements.