Comparison of accuracy in internal, marginal, and external regions of ceramic copings fabricated via milling, DLP printing, and heat-pressing methods.

OBJECTIVE: The present study aimed to evaluate the accuracy of ceramic copings fabricated by milling, DLP printing, and heat-pressing methods. METHODS: A central maxillary incisor coping was designed after scanning a typodont model. Thirty specimens were fabricated using milling (MCC), DLP printing (PCC), and heat-pressing methods (HCC) (n = 10 per group). All the specimens were scanned with a lab scanner. The scanned data were segmented into external, internal, and marginal regions and analyzed using 3D measurement software. The accuracy of each group was evaluated and Root mean square (RMS) deviations were calculated. For statistical analysis of the measurements, the Kolmogorov-Smirnov test was conducted to assess the normality and homogeneity of variance among the three groups and the results. As equal variances were not observed (p < 0.05), a nonparametric Kruskal-Wallis test was conducted, followed by post-hoc analysis using the Bonferroni-adjusted Mann - Whitney U test (alpha = 0.016). RESULTS: The MCC group recorded RMS values of 14.29 +/- 1.80 microm and 15.80 +/- 2.36 microm in the internal and marginal regions, respectively, with lower deviation (p < 0.001). The PCC group showed the highest RMS in the internal region at 39.43 +/- 4.59 microm (p = 0.684). The HCC group's RMS value was highest in the external region at 55.53 +/- 5.71 microm (p < 0.001). Statistical analyses indicated significant differences in RMS values in external and internal regions but not in the marginal region (p = 0.143). All the RMS values remained within the clinically acceptable range. CONCLUSION: This study confirmed that different fabrication techniques significantly influence the dimensional accuracy of ceramic copings. The MCC group showed lower RMS values whereas the PCC and HCC groups exhibited higher RMS values. However, all RMS values remained within the clinically acceptable range. CLINICAL SIGNIFICANCE: This study assessed the trueness and precision of ceramic copings made by different fabrication methods. The MCC group exhibited the greatest precision in both the internal and marginal regions. In contrast, the PCC group, while requiring additional research and validation in marginal areas, displayed enhanced accuracy and reproducibility in the external region compared to the HCC group.