| Summary: | Background/purpose: To evaluate the reproducibility of the marginal and internal gaps of metal copings fabricated using dental micro-stereolithography (μ-SLA), which is an additive manufacturing system. Materials and methods: A study cast of abutment tooth 46 was made from type-IV dental stone and was scanned to create a standard triangulation language file. Arrays of one (ORM), three (TRM), and six (SRM) resin copings were then fabricated on the μ-SLA build platform using investment, burnout, and casting (n = 12). The marginal and internal gaps of these metal copings were measured using a silicone-replica technique with a digital microscope (×160). The data obtained were analyzed using a non-parametric Kruskal–Wallis H test, a post-hoc Mann–Whitney U test, and a Bonferroni correction. Results: The mean and standard deviation of the marginal gap for each group were measured and found to be 81.1 and 53.2 μm, 68.3 and 44.8 μm, and 90.3 and 57.7 μm for ORM, TRM, and SRM, respectively. There were no statistical differences in the marginal gaps of the three groups (p > 0.05). Conclusion: The marginal and internal gap of ORM, TRM and SRM groups were considered clinically acceptable. Keywords: CAD/CAM, marginal gap, micro-stereolithography, Ni–Cr
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