Marginal adaptation of zirconia and porcelain fused to metal crowns fabricated by different CAD/CAM milling and lost-wax techniques: a comparative study

Objective. This in vitro study aimed to compare the marginal adaptation of monolithic zirconia crowns fabricated using two different CAD/CAM milling units (CORiTEC 150 and CERAMILL motion DRS) with porcelain-fused-to-metal (PFM) crowns produced using the conventional lost-wax technique. Methods. Thirty standardized resin models of an upper first molar were prepared and divided into three groups (n = 10 per group). Twenty zirconia crowns were milled using the CORiTEC 150 and CERAMILL motion DRS systems, while PFM crowns were fabricated using the lost-wax technique. All crowns were cemented, aged for 48 hours, and sectioned to measure marginal discrepancies at six points per specimen under 40× stereomicroscopy. Data were analyzed using independent t-tests and ANOVA followed by post hoc tests, with p < 0.05 considered statistically significant. Results. The CORiTEC 150 group demonstrated the lowest mean marginal discrepancy (55.83 ± 19.39 µm), followed by CERAMILL motion DRS (69.98 ± 20.38 µm), while PFM crowns showed the highest values (109.72 ± 42.47 µm). CAD/CAM-fabricated zirconia crowns exhibited significantly smaller marginal gaps than PFM crowns (p < 0.001). Post hoc anal