Comparative Color Stability and Surface Roughness of Five Provisional Restorative Materials Exposed to Coffee- and Tea-Based Solutions: An In Vitro Study

The optical stability and surface characteristics of provisional restorative materials are important during extended provisionalization. This in vitro study compared five commercially available provisional restorative materials exposed to five coffee- and tea-based immersion media. A balanced analytical sample of 175 disc-shaped specimens (10 mm × 2 mm) was used, with seven specimens in each material–medium subgroup. Color was measured at seven post-baseline intervals over four weeks, and surface roughness (Ra) was measured at baseline and after four weeks. Three instrumental readings were averaged for each specimen at each measurement session. Color change was significantly affected by material, immersion medium, time, and all two- and three-way interactions (all p < 0.001). Telio CS C&B showed the greatest discoloration in several media, particularly Nescafé Classic, whereas the milled PMMA products generally showed lower ΔE*ab values. Mean Ra decreased from 0.201 to 0.184 µm (p = 0.029). Surface-roughness change differed by material (p < 0.001), but not by immersion medium (p = 0.295), and the material × medium interaction was not significant (p = 0.866). The findings apply to the commercial products tested and should not be attributed to fabrication method alone.