Evaluation of accuracy of 3-dimensional printed dental models in reproducing intermaxillary relational measurements: Based on inter-operator differences.

Objective: Although, digital models have recently been used in orthodontic clinics, physical models are still needed for a multitude of reasons. The purpose of this study was to assess whether the printed models can replace the plaster models by evaluating their accuracy in reproducing intermaxillary relationships and by appraising the clinicians' ability to measure the printed models.

Methods: Twenty sets of patients' plaster models with well-established occlusal relationships were selected. Models were scanned using an intraoral scanner (Trios 3, 3Shape Dental System) by a single operator. Printed models were made with ZMD-1000B light-curing resin using the stereolithography method 3-dimensional printer. Validity, reliability, and reproducibility were evaluated using measurements obtained by three operators.

Results: In evaluation of validity, all items showed no significant differences between measurements taken from plaster and printed models. In evaluation for reliability, significant differences were found in the distance between the gingival zeniths of #23-#33 (DZL_3) for the plaster models and at #17-#43 (DZCM_1) for the printed models. In evaluation for reproducibility, the plaster models showed significant differences between operators at midline, and printed models showed significant differences at 7 measurements including #17-#47 (DZR_7).

Conclusions: The validity and reliability of intermaxillary relationships as determined by the printed model were clinically acceptable, but the evaluation of reproducibility revealed significant inter-operator differences. To use printed models as substitutes for plaster models, additional studies on their accuracies in measuring intermaxillary relationship are required.