Application of computer aided design and fused deposition modeling technology in the digital manufacture of orthodontic study models

Background: The orthodontic models can be divided into two categories, namely, working models and study models. Shaping study model is required for orthodontists. Traditionally, we shape the model with a trimmer or a base. The objective of this study was to establish the process of manufacturing orthodontic study models with the support of Computer-Aided Design (CAD) and Fused Deposition Modeling (FDM) technology, and to evaluate the accuracy of the whole process through comparing with traditional plaster models. Method: 15 sets of plaster models were divided into the mild crowding group (n=6), the moderate crowding group (n=9), and the severe crowding group (n=15). The surface data of plaster models, which was used to design the digital base in OrthoAnalyzer software, was obtained by a 3D model scanner. Through a chairside 3D printer, the designed models were converted into 3D printing models (3DP models). Linear measurements and 3D deviation analysis were taken on plaster models and 3DP models to evaluate the accuracy of the whole process. Results: Generally, 3DP models and plaster models demonstrated the same occlusion relationship and dental arch morphology. The Bland-Altman analysis results indicated that the 3DP models had excellent consistency with plaster models. The result of Kruskal-Wallis one-way analysis of variance demonstrated that the differences in crown width between the plaster models and the 3DP models among different groups showed no statistical significance (p=0.858, F=0.306). Conclusions: The environmentally-friendly and efficient manufacture process of orthodontic study model was established, and its accuracy satisfied the requirements of clinical application.