Effect of Different Solutions on the Colour Stability of Nanoparticles or Fibre Reinforced PMMA

This study aimed to evaluate the colour stability of polymethyl methacrylate (PMMA) denture base reinforced with ZrO2 nanoparticles, E‐glass fibres, and TiO2 nanoparticles at various concentrations over 180‐day storage in Steradent™ (STD) denture cleaner or coffee (CF). A total of 130 disc‐shaped specimens were fabricated at various filler concentrations and divided into four main groups to measure the colour changes. Groups Z, T, and E consisted of PMMA reinforced with ZrO2 nanoparticles, TiO2 nanoparticles, or E‐glass fibre, respectively, while Group C consisted of PMMA specimens without filler served as the control group (n = 10). The three reinforced groups were further subdivided according to the filler content (n = 10) added to the PMMA (1.5%, 3.0%, 5.0%, and 7.0% wt.%). Half of the specimens were stored in STD, while the other half was stored in CF for 180 days. A Minolta Chroma Meter was used to measure the colour changes (ΔE) at 7, 30, 90 and then 180 days. The results were assessed using two‐way repeated‐measures analysis of variance (RM‐ANOVA)  along  with  Bonferroni  post  hoc  tests  at  a  p  ≤  0.05  significance  level.  Significant  different colour changes (ΔΕ) were observed between all tested groups and across different time points. TiO2‐reinforced PMMA in coffee showed the lowest colour stability, while the E‐glass fibre‐reinforced PMMA in STD/CF showed the highest colour stability. Furthermore, coffee appeared to have the greatest impact on the CF change in comparison to the STD/CF. The results indicated that the  filler  type  and  concentration,  type  of  solution,  and  length  of  storage  all  affected  the  colour  stability of the tested specimens.