Correlation of two different measuring methods for digital models: Manual on printed paper and digital in computer: A retrospective study

Background: Digital models are considered the new standard in the clinical practice of orthodontics. However, they are difficult to use in the absence of a true scale for chairside use during clinical appointments. Therefore, an easy standardized method with true-scale paper print images would be of great utility. The aim of this study was to correlate and compare measurements obtained manually in true-scale paper printed images of digital models with those obtained digitally in the computer. Methods: Sixty desktop scanned digital models (30 upper and 30 lower) were analyzed. Ortho Insight 3D software was used for generating the printed images on paper and for measuring the digital models. Intercanine width, interpremolar width (first and second), intermolar width (first), and arch length measures were performed with both methods and were correlated and compared. Results: There was a high correlation between measurements performed with both methods. Values obtained from paper print images were lower and showed statistically significant differences (<0.4 mm; P < 0.001), which did not have any clinical implications. Conclusions: There is a high correlation between orthodontic measurements obtained manually in true-scale paper printed images of digital models and those obtained digitally in computer models, with no clinical differences between the two measurements. True-scale printed images of digital models can be used chairside in clinical appointments for the verification of measurements, or even as a guide for archwire individualization and shape bending without the need for long and complex processes or scale sizing adjustments.