Orthodontic comparison of symmetry of the dental arches by two methods: extraoral digital scanner and manual method

Abstract

Dental arch asymmetry is a common clinical finding in populations. Dental arch asymmetry is measured at pre- and post- orthodontic treatment. With the advancement of digital methods in orthodontics, new digital method needs to be evaluated and compared with the gold standard conventional method. This study aimed to evaluate accuracy and reliability of digital asymmetry measurement method. Methods: Sixty upper dental casts were analyzed using both conventional measurements with a Dr. Korkhaus grid and digital measurements using a Dentium Rainbow extraoral scanner. Transverse and anteroposterior asymmetry were measured for canines and first molars in upper arches. Statistical analysis for the comparison between two methods included: intraclass correlation coefficients (ICC), and Bland-Altman plots, Dahlberg and Relative Dahlberg Error (RDE). Additionally, to evaluate each method’s errors, ICC was performed between 4 conventional measurements for conventional method and 2 digital measurements for Digital method. Results: Two methods showed good Correlation with ICC values ranging from 97.6% to 99.0%. Bland-Altman plots indicated good agreement between methods. RDE between methods ranged from 0.214 to 0.327. The digital method yielded slightly higher values, but differences were not statistically significant. Conclusion: The digital method using an extraoral scanner provided comparable results to the conventional method. While the conventional method showed slightly higher Correlation between each measurement, which resulted by it’s weak 0.5mm scale, the digital method offers advantages in data storage and analysis. These findings suggest that digital methods can be a suitable alternative to conventional measurements in orthodontic assessments of dental arch symmetry.