Introduction:
With the increasing use of 3D printing technologies (SLA, DLP) in the fabrication of fixed prosthodontic restorations, the long-term color stability of the utilized resin materials remains a key clinical challenge. Since extrinsic staining caused by dietary chromogens is a primary reason for aesthetic failures and the subsequent need for restoration replacement, continuous evaluation of the stain resistance of modern 3D-printing dental resins is justified.

Aim of the study:
The purpose of this study was to evaluate the effect of coffee and black tea on the color stability of a 3D-printing resin used for fixed prosthodontic restorations.

Material and methods:
Fifteen truncated cone-shaped specimens were printed from the tested resin and randomly divided into three experimental groups: coffee, tea, and distilled water (control group), with 5 specimens per group. Color evaluation was performed after 3, 6, 9, and 12 days of sample immersion in the staining solutions, utilizing a colorimeter within the CIELAB color space. Color changes (ΔE) were calculated and statistically analyzed.

Results:
The immersion time in both tested solutions significantly affected the increase in ΔE values (p < 0.05). Greater material discoloration was observed in the group of specimens immersed in coffee compared to tea.

Conclusions:
Analysis according to the National Bureau of Standards (NBS) classification revealed that the resulting discolorations were clinically perceptible after just 3 days of exposure. The contact of the resin with commonly consumed beverages, namely coffee and tea, leads to progressive changes in the material’s color. Among the analyzed solutions, coffee demonstrated a higher staining potential.