Accuracy of 3D Printed Burnout Resin Versus CAD/CAM Milled Wax Castings

Objectives: The purpose of this study is to evaluate the accuracy of 3D printed burnout resin, CAD/CAM milled wax and CAD/CAM PMMA and the effect on die spacing and cementation onto the tooth. Method: Design and manufactured three different type of digital materials, PMMA, milled wax and 3D printed burnout resin (n=4/product). PMMA and milled wax were milled by MC X5 CAD/CAM machine and 3D printed resin was produced by Asiga Max. Scanning the crowns sprayed by Shera scan spray using INEOS extraoral scanner to create STL files exported for comparison with master crown. We invest (90% to 10% Shera to distal water ratio) using Shera Fina 2000 investment material and cast with Sirona PFM dental cast alloy. Devasting and grinding out the excess alloy around the crown with a 3.3 bar pressure sandblasting. Repeating the scanning processes with casted crowns and compare the STL files in cloud-compare software. Using Auto Mesh to cut half the crown to make the result accurate. Comparing both before and after casting crown in STL files using cloud-compare software and get absolute mean and RMS value for each crown. The data points on each crown is already large enough, so we don’t use p value in our study. Results: CAD/CAM milled wax, PMMA and 3D printed burnout resin all found some of the abs mean and RMS value increase before and after casting compared to master crown. Milled wax has the least difference followed by 3D printing and PMMA. PMMA is the least accurate material in this experiment which would vary the amount of die spacer and cementation. Significance: High inaccuracies of PMMA material might affect the actual die spacing and cementation value, whereas milled wax performed the best. Milled wax and 3D printed resin are both within the clinical acceptable value.