Journal of Dental Research, Vol 55, 322-327, Copyright © 1976 by International & American Associations for Dental Research Online Journals
Four variables affecting magnitude of dentrifice abrasiveness
D. B. Harte and R. S. Manly
A five-factor study was done on human dentin abrasion that involved two
abrasives, either alone or in dentifrice form, two brush brands, two brush
hardnesses, two concentrations, and two temperatures of testing. The hard
brushes caused 3.6 times as much wear as the soft brushes, a greater
influence than the abrasives compared. A brush X hardness interaction
indicated that there is a wide variation among the stiffness gradings of
toothbrushes. Tests run at 37 C were 28% less abrasive than those at room
temperature, suggesting a softening of bristles because of the warmer
temperature. A highly significant abrasive X concentration interaction
showed that dentifrices became more than twice as abrasive on dilution form
100 to 50%, but that abrasives alone did not show such changes on dilution.
The second study included two hardnesses, two abrasives, three diluents,
four concentrations, and two replicates. An interaction was found between
abrasive and diluent, showing that glycerine inhibited abrasion by 88% in
comparison with saliva and CMC. A hardness X concentration interaction
showed that wear varied widely with concentration for the hard brush but
scarcely at all for the soft brush. These findings suggest that
abrasiveness of dentifrices depends strongly on testing conditions and that
no single set of conditions is suitable for evaluating dentifrice
abrasiveness.
