Current methods of shade matching in dentistry: a review of the supporting literature.

The difficulties of shade matching in dentistry are discussed and various suggestions are given to improve the process. Several authors have described shade-taking routines with the aim of improving shade-matching. These are summarized and a method for choosing the appropriate shade from the previous guidelines is given. The scientific principles and evidence-base behind the new technique are given. The problems and advantages of instrumental shade-taking devices are reviewed.