Comparison of the marginal fit of soft-machined monolithic zirconia crowns

Aims: The aim of this study was to compare the marginal fit of five different soft machined monolithic zirconia materials. Methods: A mandibular right first molar on an acrylic model was prepared with standardized dimensions using diamond burs. Fifty metal duplicates were fabricated via laser sintering with Co-Cr alloy and divided into five groups (n=10). All duplicates were scanned using a CAD/CAM system, and zirconia crowns with a 1.5mm occlusal thickness and 20µm cement space were produced. Following sintering, marginal gaps were measured using the silicone replica technique. The obtained silicone replicas were sectioned into four parts mesiodistally and buccolingually using a scalpel. The marginal gaps of the samples were examined using a stereomicroscope under 10×magnification. Marginal gap measurements were performed at four specific points where the crown margin was closest to the cemento-enamel junction: mesial, distal, buccal, and lingual. For each crown, the measurements were repeated three times, and the mean value was recorded. A total of 600 measurements were performed for 50 crowns. Statistical analysis was conducted using one-way ANOVA and Tukey’s HSD test (p