In vitro accuracy of interim implant restorations: a comparison of two additive manufacturing methods and six surfaces

Additive manufacturing is increasingly integrated into digital workflows for interim implant-supported restorations, however evidence regarding surface-specific accuracy among printing technologies remains limited. This in vitro study evaluated the three-dimensional accuracy of interim implant-supported restorations fabricated using digital light processing (DLP) and liquid crystal display (LCD) across six anatomical surfaces. A reference restoration was generated using CAD software and exported as an STL file (reference dataset). Twenty specimens were additively manufactured ( n = 10 per group), digitized with an intraoral scanner, and superimposed onto the reference dataset using metrology software. Deviations were quantified using root mean square values (µm). Statistical comparisons were performed with Student’s t-test, two-way ANOVA followed by Tukey’s post hoc test (α = 0.05). The mean trueness was 58.71 ± 2.82 μm for DLP and 57.88 ± 4.59 μm for LCD, with no statistically significant difference ( p = .632). Precision values were 53.71 ± 2.87 μm for DLP and 56.88 ± 4.59 μm for LCD ( p = .099). No significant differences in overall trueness were observed between DLP and LCD ( p > .05). However, significant surface-dependent deviations were detected ( p < .001). DLP demonstrated greater discrepancies in the intaglio and marginal areas. Although no significant differences in overall trueness were observed between the LCD and DLP groups, the LCD group exhibited lower deviations in regions critical for restoration adaptation.