Discolouration of Polymethyl Methacrylate versus Bis???Acrylic based Provisional Crown and Bridge Dental Resins: Effect of Storage Media and Duration

Author(s):

Shivani Kohli*, Shekhar Bhatia, Kirti Sexana, Rupali Kalsi, K. Rajeshwari and Mansi Arora

Background: Provisional restorations are frequently needed for several days to weeks, demanding them to be well made and stable with distinctive functions and purposes. In aesthetically critical region, the provisional restoration must not only deliver an initial shade match, furthermore must preserve its aesthetic appearance over the service period. Noticeable colour change may compromise the suitability of provisional restorations. Aim: This study aimed to determine the discolouration of poly (methyl methacrylate) (PMMA) and bis‑acrylic based provisional crown and bridge auto‑polymerizing resins when exposed to coffee, tea, orange and cranberry juice. Materials and Methods: Four auto-polymerizing provisional crown and bridge resins, two methyl methacrylate and two bis-acrylic were used. Specimens were randomly divided into five groups (N=120, n=30) to be stored in artificial saliva, artificial saliva+tea, artificial saliva+coffee, artificial saliva+orange juice and artificial saliva+cranberry juice. Colour measurements were taken before immersion, after 1 week and 1 month of immersion with the Spectrophotometer. Data were analysed using analysis of variance (ANOVA), independent samples t‑test, Scheffe’s post‑hoc test, and paired t‑test. A significance level of a = 0.05 was used for all statistical analyses. Results: After the immersion period of 1 week and 1 month period, the post hoc analysis indicated that highest ΔE values were observed for Protemp II-artificial saliva + coffee as compared to other materials. Conclusion: The degrees of discolouration increased with immersion time. Methyl methacrylate resins were more resistant to discolouration than bis-acrylic resins. After immersion for 1 month, artificial saliva + coffee solution resulted in unacceptable discolouration for all the tested materials.