Influence of build-plate position and sequential printing on the colour fidelity of vat-photopolymerised microhybrid resins

Abstract Contemporary vat-photopolymerisation workflows often assume spatial colour uniformity across the build plate and consistent production outcomes across sequential print runs. This study evaluated these assumptions using two dental microhybrid resin workflows: Saremco Print Crowntec (SPC), a Bis-EMA-based ceramic hybrid resin, and Asiga DentaTooth (ADT), a UDMA-based resin. A total of 216 discs were printed in a 3 × 12 grid across three sequential print runs per material. Target-referenced intrinsic colour deviation was quantified as ΔE₀₀ in Specular Component Included (SCI) mode and mapped by build position and print run. For each material/run combination, Disc #1 was measured initially to establish the run-specific SCI target L*, a*, and b* coordinates, then remeasured as one of the 36 samples included in the analysis. Mean ΔE₀₀ was 0.35 ± 0.12 for SPC and 0.23 ± 0.10 for ADT, with maximum values of 0.73 and 0.46, respectively. SPC exhibited local excursions, most notably at Position 33 in Run 1 and Position 24 in Run 2, without evidence of a systematic centre-periphery effect in the runs evaluated. ADT showed lower overall spatial deviation but a V-shaped descriptive profile in within-run deviation. Because each run represented a single printing event and was evaluated against a run-specific target, sequential differences were interpreted descriptively and do not establish generalisable run-order effects or absolute colour drift. All observed values remained below PT₅₀ ≈ 0.8 and well below AT₅₀ ≈ 1.8. Likewise, as processing protocols differed between materials, cross-material contrasts were interpreted as material-specific workflow observations. Both workflows demonstrated high short-term intrinsic colour consistency under the tested conditions, while the observed spatial variation supports attention to resin homogenisation and build-plate process control.