Journal of Dental Research, Vol 68, 1781-1785, Copyright © 1989 by International & American Associations for Dental Research Online Journals
The measurement of toothbrush wear
H. R. Rawls, N. J. Mkwayi-Tulloch, R. Casella and R. Cosgrove
Gillette Company, Boston Research & Development, Gillette Park, Massachusetts 02106-2131.
Toothbrushes wear out and progressively lose their ability to clean as the
bristles abrade and become curled and matted. To study the factors that
influence this process, we developed a quantitative measure of bristle
splaying (wear index) and a method for judging and ranking the overall
state of brush deterioration (wear rating) and used these to determine the
effects of the individual user, brush design, time in use, and bristle
material. Wear index is the average increase in brush-head dimensions
normalized for maximum bristle length, and is dimensionless. Wear rating is
a subjective means of classifying the increasing severity of deterioration
on a scale of 0 to 3. The wear characteristics of a variety of commercial
and experimental brushes with different design features were determined.
Test variables were time in use, brush design (e.g., geometry and size of
the brush head), and bristle composition. Time of use, the individual user,
and bristle composition were found to have the strongest influences on
splaying, and brush design was found to have the least influence. The wear
index offers a quantitative means of comparing brushes of different
dimensions at various stages of splaying. The wear rating, although
qualitative, is a quick means of ranking brushes in various stages of
deterioration. The two methods correlate (R2 = 0.87), and both are
sensitive to several factors that affect brush durability. Therefore, these
methods appear to be suitable not only for research, but also for quality
control, the setting of standards, and for substantiation of advertising
claims.
