Evaluation of the Trueness and Precision of Cast, Milled-Cast, Milled, and 3D-Printed Post-and-Core Techniques Using...

BACKGROUND Accurate adaptation of post-and-core restorations is critical for optimal stress distribution, retention, and long-term prognosis of endodontically treated teeth. While conventional lost-wax casting remains widely used, digital workflows such as computer-aided design/computer-aided manufacturing (CAD/CAM) milling and 3-dimensional (3D) printing have emerged as alternative fabrication methods. MATERIAL AND METHODS This in vitro study evaluated the trueness, precision, and clinical tolerance of 4 fabrication techniques using 3D deviation analysis. A standardized digital model of a maxillary central incisor with a 10 mm post space was used to generate the reference standard tessellation language (STL) file for the corresponding post-and-core restoration. Forty post-and-core specimens were fabricated (n=10/group): (I) conventional casting, (II) milled wax-cast, (III) CAD/CAM-milled zirconia, and (IV) 3D-printed zirconia. Specimens were scanned using a high-resolution laboratory scanner and analyzed with digital metrology software. Trueness was assessed using root mean square (RMS) deviation, precision by standard deviation of RMS values, and clinical tolerance by the percentage of points within ±100 µm. RESULTS Conventional casting demonstrated significantly superior trueness (0.299±0.047 mm) and the highest clinical tolerance (3.9). All digital workflows exhibited significantly greater RMS deviations (P<0.001), with 3D-printed zirconia showing the lowest trueness. Precision differed significantly among groups (P<0.001), with conventional casting showing greater reproducibility, while milled and 3D-printed zirconia demonstrated comparable precision. Clinical tolerance remained low across all groups. CONCLUSIONS The conventional casting technique offered greater relative trueness and precision than the evaluated digital workflows. However, the absolute clinical accuracy across all groups was suboptimal. Despite workflow advantages, digital methods require further optimization to achieve clinically acceptable trueness, precision, and reliability.