Color stability of provisional crown and fixed partial denture resins

Statement of problem. Provisional resins are used extensively during fixed prosthodontic treatment and exhibit varying degrees of color change/discoloration over time. Data are needed to help predict color stability of provisional resins. Purpose. The purpose of this in vitro study was to measure the color change of 12 provisional prosthodontic materials after immersion in artificial saliva and artificial saliva-coffee solutions for 1, 2, and 4 weeks. Material and methods. Twelve provisional materials were studied. Methacrylates consisted of Alike, jet, Temporary Bridge Resin, Unifast, and Zeta CC. Bis-acryl resins included Instatemp, Integrity, Luxatemp, Protemp Garant, Provipont, Provitec, and Temphase. Tell specimens (25.4 mm x 25.4 mm x 2.4 mm) of each material were fabricated. Five specimens were stored at 37degreesC in artificial saliva and 5 were stored in a solution of artificial saliva (400 cc) and coffee (800 cc). Baseline color was measured using a colorimeter. Further color measurements were made after 1, 2, and 4 weeks of immersion. CIE L*a*b* values were recorded and color differences (DeltaE) between baseline and each storage interval were calculated using a 2-way ANOVA with Bonferroni adjustment for multiple comparisons in conjunction with all overall alpha=.05. Results. Results indicated the presence of strong interaction between material and storage solution regardless of the aspect of color considered (P<.0001 for DeltaE, DeltaL*, Deltaa*, and Deltab*). Coffee solution relative to saliva solution had the most significant impact on color change for Luxatemp, Protemp, and Temphase materials at 4 weeks, but the greatest overall color change for both coffee and saliva solutions was found for Provipont (DeltaE = 9.40 coffee; 8.51 saliva) and the least overall color change for both solutions was found for Zeta CC (DeltaE= 0.31 coffee; 0.23 saliva). Conclusions. Under the conditions of this study, 12 provisional crown and fixed partial denture resins demonstrated varying tendency to discolor over a range of time periods when immersed in artificial saliva and artificial saliva-coffee solutions.