Dental plaque is the precursor to many oral diseases (e.g. gingivitis, peri
odontitis, caries) and thus its removal and control are an important aspect
of oral hygiene. Many of the oral care products available today remove or
inhibit the growth of dental plaque. Historically, the antiplaque efficacy
of products was measured in blinded clinical trials where the amount of pla
que on teeth is assessed via subjective visual grading with predefined scal
es such as the Turesky index. The ability of the examiner to consistently a
pply the index over time and the sensitivity of the scales often leads to l
arge, expensive clinical trials. The present invention is an automatic meas
urement of plaque coverage on the facial surfaces of teeth using a digital
image analysis technique. Dental plaque disclosed with fluorescein is digit
ally imaged under long-wave, ultraviolet light. Ultraviolet illumination of
fluorescein-disclosed plaque produces an image where the pixels of the ima
ge can be categorically classified based on color into one of five classes:
teeth; plaque; gingiva; plaque on gingiva, or lip retractors. The amount o
f plaque on teeth can be determined by summation of the number of plaque pi
xels. The percent coverage is calculated from the number of plaque pixels a
nd teeth pixels in the image. The digital image analysis of plaque allows f
acial plaque levels to be precisely measured (RSD=3.77%). In application, t
he digital image analysis of plaque is capable of measuring highly signific
ant plaque growth inhibition of a stannous fluoride dentifrice with as few
as 10 subjects in a cross-over design. Introduction Copyright (C) 2000 S. K
arger AG, Basel.