Tooth whitening has little or no effect on restorative materials such as fillings, porcelain or crowns, but in real time it temporarily reduces the bond strength between enamel and composite restorations. Therefore, it is a good idea to check with your dental professional before beginning any course of tooth whitening. It is important to communicate well so that everyone knows the pros and cons of any treatment, but typically its easy to get good results when things are planned well.