Accuracy and reproducibility of 3-dimensional digital model measurements

Introduction: The purpose of this study was to evaluate the reliability of measurements made on 3-dimensional digital models obtained with a surface laser scanner (D-250; 3Shape, Copenhagen, Denmark). Methods: Twenty orthodontic dental casts of permanent dentitions were selected. Three-dimensional images were obtained on this scanner and analyzed by using the Geomagic Studio 5 software (Raindrop Geomagic, Inc, Morrisville, NC). Measurements were made with a digital caliper directly on the dental casts and also digitally on the digital models. Fifteen anatomic dental points were identified, and a total of 11 linear measurements were taken from each cast, including arch length and width. Dependent t tests were used to evaluate intraexaminer reproducibility and measurement accuracy on the digital models. Results: No statistically significant differences were found between the measurements made directly on the dental casts and on the digital models. Conclusions: Linear measurements on digital models are accurate and reproducible. Digital models obtained with the surface laser scanner are reliable for measurements of arch width and length. (Am J Orthod Dentofacial Orthop 2012;142:269-73)