Influence of temperature on the dimensional stability of DLP- and FDM-printed dental casts with different base designs

To measure and evaluate the influence of temperature on the dimensional stability of additively manufactured (AM) dental casts printed with different additive manufacturing technologies and different cast base designs. A total of 90 physical maxillary casts were constructed for solid, hollow and honeycomb AM casts (n=10/group) using three materials with the digital light projection (DLP) printer (DentaModel - basic cast, DentaForm-heat resistant cast resins) and fused deposition manufacturing (FDM) printer (SIMPLEX-Biofilament resin). After printing and post-curing, the casts were heated twice in a pressure pot for 20 minutes at 55°C and were scanned three times; after printing, first heating (20 minutes) and after second heating (40 minutes) to simulate adjustments or addition of acrylic, usually done for orthodontic appliances. All scanned files were analyzed in 3D comparison metrology software. Data were statistically analyzed, and surfaces were analyzed under scanning electron microscopy (SEM). DentaModel and DentaForm showed significantly less (P < 0.0001) overall accuracy compared to SIMPLEX Model, displaying higher dimensional stability after heating. RMS of SIMPLEX cast increased significantly after the first and second heating. RMS of DLP cast showed stable changes over time and repeated heating, below the clinically acceptable threshold of 250 μm for orthodontic applications. DLP cast retained higher dimensional stability after heating compared to FDM casts. Hollow casts produced using SIMPLEX biofilament were the least accurate after heating, while the most accurate were solid casts produced using DentaModel resin. Hollow casts manufactured DLP technology were clinically acceptable after heating; therefore, they can be used alternatively to solid casts to save time and materials. Results from this study highlight the possibility of using AM casts and the importance of technology, material and base design when producing a dimensionally accurate and stable AM cast.