Dimensional Change of Denture PMMA Processed to CAD/CAM Produced Denture Bases

Purpose: The purpose of this study was to carry out a three-dimensional analysis of the processing distortion that occurs when acrylic resin and teeth are processed onto two types of CAD/CAM denture bases. Previous studies used analog methods of measurement, and have not examined CAD/CAM denture base distortion after processing. \nMaterials and Methods: Ten milled and printed denture bases were fabricated on an edentulous cast, the intaglio surface scanned, and then a second processing step with acrylic resin and teeth was performed to finish fabrication of complete dentures. The samples were scanned a second time after the second processing step and then both pre- and post-processed STL files of the intaglio surface were compared with the original design file by digital file superimposition to record distortion in twelve anatomic regions. \nResults: Both milled and printed denture bases had statistically significant changes (p<.001) after processing. Milled denture bases had an average deviation from the design file before processing of -82.5 µm and -2.3 µm after. Printed denture bases had an average deviation from the design file before processing of -100.2 µm and 23.3 µm after. Comparison between denture base groups showed a significant difference (p<.05) in distortion; milled denture bases distorted less than printed denture bases. \nConclusions: There was a significant difference in denture bases after processing regardless of fabrication method, with more distortion seen in printed denture bases. This difference, while statistically significant, may not be clinically significant. The area of the smallest distortion after processing was the posterior palatal seal for both milled and printed denture bases. The area of greatest distortion after processing for the printed bases was the tuberosity region, for the milled bases the mid palate region exhibited the greatest value of distortion.