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Development of a quantitative measurement to assess the whitening effects of two different oxygenating agents on teeth in vivo.

A new approach to assess color change in teeth involves application of the Minolta CR-221 Chroma Meter. The process has been assessed in vitro by Dr. Stephen Rosenstiel of Ohio University and by Dr. Robert Seghi of the University of California School of Dentistry. The purpose of this study was to develop a technique to assess the tooth-whitening effects of peroxides on teeth in vivo, using a small-area colorimeter. Twenty male and female subjects participated. Study casts were made from alginate impressions. Two maxillary, white, polyvinyl siloxane, custom-postioning splints were fabricated for each subject. Each splint was modified to accept exactly the head of the colorimeter to a window exposing the middle one third of the facial surface of one central incisor. The coloimeter converts all colors within the range of human perception into a common numerical code. The use of the positioning splint allowed the researchers to reposition the colorimeter precisely for multiple reading each time measuremehts were taken. The color parameters were recorded in the L*a*b* color space. This method shows that multiple measurements on the same subject are consistent and statistically accurate. The standard deviation for L* (lightness) values was 0.22. This technique showed quantitatively the whitening effect on teeth to be increase in L* and a decrease in a* (red) and b* (yellow). The mean color difference (deltaE) for the 3-week study was 5.07.