THE MEASUREMENT OF THE ABRASION OF HUMAN TEETH BY DENTIFRICE ABRASIVES: A TEST UTILIZING RADIOACTIVE TEETH

¹ The Procter & Gamble Company, Miami Valley Laboratories, Cincinnati, Ohio

A procedure for the measurement of either enamel or dentin abrasion by the use of human teeth made radioactive by mild neutron irradiation is described. The method is more precise and faster than former methods dependent upon the measurement of the depth of a groove cut into tooth structure. The results are obtained directly in terms of the amount of human tooth structure worn away by a toothbrush and dentifrice abrasive slurry operating at a known, constant brush pressure and a constant stroke speed. The coefficient of variation of the test is 6-7 when 8 replications are carried out, and 10-15 when only duplicates are run as in the usual routine testing. This is one half to one fourth of the variation involved in the depth-of-cut method and results can be obtained with an expenditure of one half to one third of the time of the former method.

Test results are given for aqueous slurries of dentifrice grade calcium carbonate, dicalcium phosphate (dihydrate and anhydrous), and insoluble sodium metaphosphate.