Validity and reliability of measurements of the parameters of smile aesthetics: a comparison between digital and plaster models

This study aims to evaluate the validity and reliability of the TRIOS3 Color intraoral scanner (3Shape A/S, Copenhagen, Denmark) and its associated Ortho Analyzer™ software in measuring parameters of smile aesthetics compared with measurements on plaster casts. The study sample comprised plaster casts and digital models obtained from 30 subjects. Height (H), mesiodistal diameter (MDD) and connecting space (CS) of the anterior teeth were measured with a digital calliper on the plaster models and with the orthodontic software on the digital models. Validity was assessed using a 2-tailed paired t-test; the reliability of measurements for intra-examiner was evaluated with the Intra-class Correlation Coefficient (ICC). There were no statistically significant differences between the measurements made with the two methods. The ICC is 99% for height and MDD measurements, slightly lower in the evaluation of the CS. Linear measurements made on digital model have clinically acceptable accuracy and reliability. The TRIOS3 Color intraoral scanner represents a valuable tool for dental practice, particularly in evaluating parameters of smile aesthetics.