Accuracy of 3D printing Versus Milling in Fabrication of Clear Aligners Dental Models

Objective: This study was conducted to compare two techniques for fabricating dental models with attachments (additive 3D printing versus subtractive milling). Materials and Methods : a random model was selected and scanned with an intraoral scanner Medit I600 and the STL file of the model was used to create another STL file of a new model with rectangular attachments on the labial and buccal surfaces of the anterior and posterior teeth respectively was created by Maestero software. The new STL file was 3D printed three times by the same 3D printer (Anycubic mono X) to produce 3D printed models that consitituted group 1. Three 3D printed discs were created by the same 3D printer with dimensions matching the discs of the milling machine. Group 2 consisted of three milled models that were fabricated by a milling machine ROLAND 51 ( Kemet corporation, Cairo, Egypt). The models of both groups were scanned with the same intraoral scanner Medit I600, and the STL files generated were superimposed over the original STL file by the same software (cloudcompare). The linear deviations of attachment position, measured in millimeters, were as follows; A) Mesio-distal: The X-axis movement B) Occluso-gingival: The Z-axis C) Bucco-lingual: The Y-axis movement. One way ANOVA and t tests were used to compare the deviation within each group and between the two groups, the significant level was set at p-value < 0.05 . Results: statistically significant differences between the molars, incisors, canines, and premolars were observed in both groups in all ways of space. Comparing the two groups revealed a non statistically significant difference between both groups. Conclusion: 3d printing provided a more economic and less time and material wasting way for fabrication of clear aligners models with attachments than milling