Dental Casts for Fixed Dental Prostheses Printed with SLA Technology: Influence of External Shell Thickness and Printing Orientation.

Printed cast models are becoming increasingly important in prosthodontics. The aim of this in vitro study was to evaluate the influence of print orientation and external shell thickness on the accuracy of stereolithography (SLA) master casts for fixed dental prostheses. Seventy-two maxillary hollow master casts were fabricated from a standard tessellation language (STL 0) reference file containing dental preparations. The casts were divided into six groups (n = 12 per group) according to internal shell thickness (2 mm and 4 mm) and print orientation (0°, 10°, and 20°). Discrepancies between STL 0 and the STL files of the printed casts were measured using the root mean square (RMS) error. Data were statistically analyzed using a one-way Kruskal-Wallis test to assess trueness, and precision was evaluated with the Levene test (α = 0.05). No statistically significant differences were found in any of the tested conditions. Print orientation and cast thickness did not influence the overall accuracy of SLA master casts for fixed dental prostheses.