[Preliminary investigation on the effect of zirconium-based colorants on the colorimetric properties of fused deposition modeled polyetheretherketone composites].

Objective: To analyze the effect of zirconium-based pigments with different mass fractions on the colorimetric properties of fused deposition modeling (FDM) polyetheretherketone (PEEK) composites, and to investigate the feasibility of using these pigments for computer color matching of PEEK composites. Methods: Specimens were fabricated using FDM technology, comprising two control groups [Pure PEEK group, PEEK-TiO₂ group (PEEK compounded with 20% TiO₂)] and nine experimental groups based on the type of zirconium-based pigment (zirconium praseodymium yellow, zirconium iron red, zirconium vanadium blue) and mass fraction (0.1%, 0.5%, 1.0%). The experimental group specimens consisted of PEEK blended with 20% TiO₂ and the respective zirconium-based pigment. The spectral reflectance curve and chromaticity values of all specimens were measured using a spectrophotometer. The relationship between the chromaticity values of each colored PEEK composite in the experimental groups and the pigment mass fraction was determined. Shade guide tabs mimicking clinically used tooth shades were fabricated using a light-curing resin (Filtek Z350XT Body). The full-spectrum color matching method was employed to calculate the PEEK composite formulations (PEEK, 20% TiO₂, blends of the three zirconium-based pigments) required to match these target tooth shades. Verification group specimens based on these calculated recipes were then fabricated. The color difference between each verification group specimen and its corresponding target shade tab was calculated. Color differences between the target shade tabs and the two control groups (Pure PEEK, PEEK-TiO₂) were also calculated. Results: The spectral reflectance curves of PEEK composite specimens containing different types of zirconium-based pigments exhibited distinct characteristic features. The chromaticity values were significantly affected by the mass fraction of the same zirconium-based pigment. Based on computer color matching calculations, the color differences between the verification group specimens and the target shade tabs ranged from 1.59 to 14.55. Conclusions: This study demonstrates the feasibility of utilizing the three zirconium-based pigments (zirconium praseodymium yellow, zirconium iron red, zirconium vanadium blue) for full-spectrum computer color matching of PEEK-TiO₂ composites.