Effect of Whey Protein Isolate and Concentrate Shakes on Surface and Optical Properties of 3D-Printed Definitive Resins

This in vitro study evaluated the effects of whey protein isolate and concentrate on surface roughness, color stainability, and translucency of 3D-printed definitive resins. Five 3D-printed resins were tested: Alias Dental Crown (AC), Crowntec (CT), Permanent Crown Resin (PC), VarseoSmile Crownplus (VSC), and VarseoSmile TriniQ (VST) (n = 30). Each material was subdivided into groups (n = 10), and the same specimens were evaluated at baseline, after 3 and 14 days of immersion in distilled water, whey protein isolate, or whey protein concentrate. Surface roughness (Ra) was measured with a contact profilometer, while color stainability (ΔE00) and translucency (ΔRTP00) were assessed using a spectrophotometer. Surface roughness was not significantly affected by solution type, with minor material-specific increases limited to AC and VST (p = 0.001). Color stainability differed significantly among solutions (p = 0.001) and increased significantly between 3 and 14 days (p = 0.001), with whey protein concentrate producing the greatest discoloration. At 14 days, AC demonstrated the highest ΔE00, followed by CT, while PC, VSC, and VST showed comparable performance. Translucency changes differed significantly among materials (p = 0.001), with AC exhibiting the lowest ΔRTP00 in protein solutions, exceeding the perceptibility threshold but remaining below the acceptability threshold. Whey protein shakes increased color stainability of certain resins, with AC, CT, and VST exceeding the color acceptability threshold (AT00 = 1.81), while surface roughness changes were limited and translucency remained within the acceptability threshold for all materials.