ABSTRACT
There are several designs that can be used depending on the nature and location of the discoloration and the specific case (Haywood 1991). For example if the front teeth are particularly dark and discoloured while the colour of the rest of the teeth is satisfactory a tray can be designed to lighten the central incisors only. Conversely, windows can be cut into the trays to exclude certain teeth (see Figures 6.14 and 6.27).
