Methodological accuracy of digital and manual model analysis in orthodontics - A retrospective clinical study.

Introduction: Computer-based digital orthodontic models are available for clinicians, supplemented by dedicated software for performing required diagnostic measurements. The purpose of this study was to evaluate the accuracy of measurements made on three-dimensional digital models obtained with a CBCT-scanner (DigiModel™, OrthoProof(®), Nieuwegin, The Netherlands).

Methods: 66 orthodontic dental casts of primary and early mixed dentitions were selected. Three-dimensional images were obtained on this CBCT-scanner and analyzed by means of the DigiModel™ software. Measurements were made with a digital caliper directly on the conventional casts and also digitally on the virtual models. 6 anatomic dental points were identified, and a total of 11 measurements were taken from each cast, including midline deviation, overjet, overbite and arch widths. Conformity of digital and manual measurements as well as intra-, inter- and repeated-measurement-reliability were evaluated by Lin's Concordance Correlation Coefficient, ICC and a Bland-Altman-analysis.

Results: The agreement and conformity of digital and manual measurements was substantial for all parameters evaluated. Intra-, inter- and repeated-measurement-reliability was excellent.

Conclusions: Measurements on digital models obtained by a CBCT scan of conventional casts (DigiModel™, OrthoProof(®)) are suited for reliable diagnostic measurements, which compare well to those obtained from plaster casts, the current gold standard.