title: Build Angle: Does It Influence the Accuracy of 3D-Printed Dental Restorations Using Digital Light-Processing Technology?
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of the build orientation/build angle on the dimensional accuracy of full-coverage dental restorations manufactured using digital light-processing technology (DLP-AM).
  
  
  METHODS
  A full dental crown was digitally designed and 3D-printed using DLP-AM. Nine build angles were used: 90, 120, 135, 150, 180, 210, 225, 240, and 270 degrees. The specimens were digitally scanned using a high-resolution optical surface scanner (IScan D104i, Imetric). Dimensional accuracy was evaluated using the digital subtraction technique. The 3D digital files of the scanned printed crowns (test model) were exported in standard tessellation language (STL) format and superimposed on the STL file of the designed crown [reference model] using Geomagic Studio 2014 (3D Systems). The root mean square estimate (RMSE) values were evaluated, and the deviation patterns on the color maps were further assessed.
  
  
  RESULTS
  The build angle influenced the dimensional accuracy of 3D-printed restorations. The lowest RMSE was recorded for the 135-degree and 210-degree build angles. However, the overall deviation pattern on the color map was more favorable with the 135-degree build angle in contrast with the 210-degree build angle where the deviation was observed around the critical marginal area.
  
  
  CONCLUSIONS
  Within the limitations of this study, the recommended build angle using the current DLP system was 135 degrees. Among the selected build angles, it offers the highest dimensional accuracy and the most favorable deviation pattern. It also offers a self-supporting crown geometry throughout the building process.
authors.forename: Reham B
authors.initials: RB
authors.lastname: Osman
authors.forename: Nawal
authors.initials: N
authors.lastname: Alharbi
authors.forename: Daniel
authors.initials: D
authors.lastname: Wismeijer
mesh_terms: D017076:Computer-Aided Design; D003442:Crowns; D017267:Dental Prosthesis Design; D006801:Humans; D008027:Light; D008422:Materials Testing; D066330:Printing, Three-Dimensional; D015203:Reproducibility of Results