1. When fabricating a provisional restoration by mixing the polymer and the monomer, color instability of the restoration can result. In time, the restoration may become more yellow in appearance. What is the cause?
a. The monomer present is urethane dimethacrylate.
b. The polymer used was methyl methacrylate.
c. Curing the restoration in water at 100° C.
* d. Unreacted benzoyl peroxide is present.
e. None of the above.
Answer: d.