Influence of the three-dimensional printing technique and printing layer thickness on model accuracy.

OBJECTIVE: The accuracies of three-dimensional (3D) printed dental models using various digital light processing (DLP) and stereolithography (SLA) printers at different thicknesses were compared. MATERIALS AND METHODS: Based on digital dental models (originally digitized using R700; 3Shape, Copenhagen, Denmark), physical dental models were printed using three types of DLP printers: (1) EvoDent (UnionTec, Shanghai, China) with layer thicknesses of 50 mum and 100 mum; (2) EncaDent (Encashape, WuXi, China) with layer thicknesses of 20, 30, 50 and 100 mum; (3) Vida HD (Envisioned, Dearborn, MI, USA) with layer thicknesses of 50 and 100 mum. Models with the SLA printer Form 2 (Formlabs, Somerville, MA, USA) were printed with layer thicknesses of 25, 50 and 100 mum. All 22 printed models were converted to digital dental models using a D2000 model scanner (3 Shape, Copenhagen, Denmark) and compared three-dimensionally to the source files using Geomagic Qualify 12.0 (3D Systems, Rock Hill, SC, USA). RESULTS: The printing accuracy of all printers was higher at 50 mum. When the layer thickness was set at 100 mum, the printing speed and printing accuracy of DLP printer were both superior to those of the SLA printer. In all groups, the EvoDent 50 mum group had the highest consistency with the source files (mean absolute deviation of 0.0233 mm in the maxilla and 0.0301 mm in the mandible). While the accuracy of Form 2 100 mum group was the lowest (mean absolute deviation of 0.0511 mm in the maxilla and 0.0570 mm in the mandible). CONCLUSION: For the 3D printers studied, 50 mum was the optimum layer thickness for DLP technology, and the printing accuracy using SLA technology increased with decreasing layer thickness. The DLP technology also had higher printing accuracy at a layer thickness of 100 mum. EvoDent 50 mum had the highest and Form 2 100 mum the lowest printing accuracy.