Trueness and the amount of clinical adjustment for zirconia crowns fabricated by digital light processing at different build angles: a within-patient clinical study

PURPOSE: This clinical study evaluated the effect of build angle (0°, 45°, and 90°) in digital light processing (DLP) printing on the trueness and chairside adjustment of zirconia crowns and compared these outcomes with conventionally milled crowns. MATERIALS AND METHODS: Ten patients each received one milled zirconia crown and three DLP-printed zirconia crowns fabricated at 0°, 45°, and 90° build angles (40 crowns total; four crowns per patient). Trueness was calculated as the root mean square (RMS) surface deviation between intraoral scans of the crowns and the CAD design. Occlusal and intaglio adjustments were quantified as the RMS deviation between pre- and post-adjustment scans. Data were analyzed using linear mixed-effects models with manufacturing method as a fixed effect and patient as a random intercept to account for within-patient clustering. Post hoc comparisons were performed using Tukey-adjusted pairwise contrasts of estimated marginal means (α = .05). CONCLUSION: Compared with milling, DLP-printed zirconia crowns demonstrated greater trueness (lower RMS) and required less chairside adjustment. Under the tested conditions, a 0° build angle was associated with the lowest trueness RMS and the least adjustment requirements.