Three-Dimensional Accuracy Evaluation of Two Additive Manufacturing Processes in the Production of Dental Models

Abstract

In the current orthodontic and prosthodontics practice, study models made of plaster are being used to provide a three-dimensional view of the patient’s occlusion and allow the clinician to analyze, diagnose, or monitor anomalies. With the introduction of intraoral and extra oral digital impressions, it is now possible to obtain digital study models of the patients’ dental arches. Digital models can be obtained in a physical hardcopy via 3D printing or rapid prototyping. Although, professional 3D printers require a high initial set-up cost, low cost 3D printers can provide similar quality products. The aim of this study is to investigate the accuracy of physical dental models reconstructed from digital data by two rapid prototyping techniques. For this purpose twenty mandibular and maxillary conventional plaster models from randomly chosen subjects were selected and served as the gold standard. The casts were digitized using a 3D scanner and .stl surface models were acquired; the virtual model was adjusted for reconstruction using dedicated software, thus obtaining the CAD model of the casts. The CAD models were reconstructed using a 3D fused deposition modeling (FDM) printer, a RepRap FDM printer and an inverted stereolithography printer. The reconstructed models were digitized using a laboratory 3D scanner and the resulting Mesh datasets were compared with the CAD model using inspection software. The mean systematic differences for the 3D comparison of the reconstructed models were 0.207 mm for the stereolithography models, 0.156 mm for the FDM models, and 0.128 mm for the RepRap models. Although a technology proved the ability to manufacture a dental model with accentuated morphology, the results demonstrate that replicas of plaster casts are influenced by problems linked to the size of the detail to be reproduced, which is often similar to or finer than the fabrication layer.