Influence of Orthodontic Brackets and Wires on Intraoral Scan Accuracy: An In Vivo Study

This study evaluated and compared the accuracy of conventional alginate impressions and intraoral scans for orthodontic measurements and full-arch superimposition under clinical conditions with brackets and wires present. Intraoral scanners are increasingly used in orthodontics due to their advantages in efficiency, patient comfort, and digital workflow integration. However, concerns remain regarding their accuracy under clinical conditions, particularly in the presence of brackets and wires, which may introduce scanning artifacts. In vivo evidence evaluating their impact across sequential orthodontic stages remains limited.

This in vivo study employed a within-subject comparative design, with conventional alginate models serving as the reference standard. Fifteen participants requiring orthodontic treatment were enrolled in this study. Five study models from each subject were obtained from (1) conventional alginate impression (Con), (2) intraoral scanning (Ios), (3) conventional alginate impression, (4) intraoral scanning after bonding with orthodontic brackets (ConBk and IosBk), and (5) intraoral scanning in subjects who were bonding with orthodontic brackets and wire insertion (IosBkW). The Con and ConBk models were poured and digitized using a laboratory scanner, while the intraoral scan data were exported as STL (Standard Tessellation Language) files. Linear measurements and superimposition analysis were performed in Ortho Analyzer software. Superimposition was performed using a landmark-guided registration protocol with standardized cross-sectional planes. Deviations were quantified as the maximum linear distance between corresponding cross-sectional profiles. Statistical comparisons were analyzed using Welch's analysis of variance and Games-Howell post hoc tests (p < 0.05).

No statistically significant differences were observed in linear measurements between digital models obtained from intraoral scanners and conventional reference models across all orthodontic stages (p > 0.05). Intercanine and intermolar widths in both maxillary and mandibular arches showed high agreement with the conventional reference models, with minimal variations across conditions. For superimposition analysis, small but statistically significant deviations were detected in models with brackets and wires compared with the conventional reference (p < 0.001). However, these deviations were minor (-0.17 to -0.20 mm) and remained within clinically acceptable limits.

Intraoral scanning can be confidently used throughout fixed-appliance therapy without removing brackets or wires when standardized scanning protocols are followed.