Overall fit of anterior and posterior single crown substructures fabricated with different additive manufacturing and conventional techniques

Marginal and internal fit of single crowns is critical for clinical success. Further research is necessary to investigate the effects of various conventional and additive/subtractive manufacturing techniques on restoration fit, particularly for different tooth types. This in vitro study compared the fit of anterior and posterior crown substructures fabricated using five techniques: milled wax patterns for casting (CAW), 3D-printed polymer patterns for casting (3DP), direct metal laser sintering (DMLS), selective laser melting (SLM), and manual wax carving (Cast). The maxillary lateral and first molar teeth were prepared on a polyamide model, and substructures were designed after scanning. Cobalt-chromium (Co-Cr) specimens were fabricated for each technique (n = 10). Discrepancies were measured using the silicone replica technique and analyzed with two-way ANOVA and Bonferroni tests (α =.05). The 3DP group exhibited the highest overall discrepancies, while DMLS had the highest for molars, and DMLS, Cast, and SLM had the highest for laterals, respectively (p < 0.05). Tooth type significantly affected chamfer (p = 0.023, partial η² = 0.283), axial (p = 0.009, partial η² = 0.017), and incisal/occlusal discrepancies (p < 0.001, partial η² = 0.083). Significant differences were noted among fabrication techniques regarding overall, marginal, chamfer, axial, and incisal/occlusal discrepancies (p < 0.001). The DMLS technique showed results comparable to manual wax carving, demonstrating superior marginal and internal adaptation in posterior substructures (p < 0.05).