Clinical assessment of the colour stability of resin filling materials

The clinical estimation of colour stability depends on the quality of illumination and visibility (Table I). Every observer should be aware that not only the eye but also he himself has several shortcomings. In clinical research the precision can be raised by well-defined characteristics, by recording the initial stage and by trained investigators. There are no suitable instruments for determining the colour of curved and partially hidden restorations or of the confluent shades of teeth. As indicated in Fig. 2 visual inspection renders results which characterize the resin material. For the patient minor discolourations are often hidden by not uniform illumination and reflections.