PARAMETERS FOR ASSESSING TOOTHPASTES 217 gO- 70- 50- - 30- 10- -10- -30 0 +++++ I I I I -20 -40 -60 SV (rel. units) Figure 1. Scratching (SV) and polishing values (PV) of 20 different European and American toothpastes (+) and test products I-VI (*). Figure 3 shows the RDA and REA values of the test products. The RDA values are very low and barely increase with a rising polishing alumina content. In contrast, test product I with only 1% polishing alumina has a high enamel abrasiveness. With higher polishing alumina contents, enamel abrasion increases sharply in a linear fashion. With increasing contents of polishing alumina, cleaning values determined for test products I-VI also improve, as can be seen from Figure 4. In a manner similar to that of the polishing effect, the curve flattens out with higher polishing alumina contents and tends towards a limit value. High correlation coefficients can be calculated for the dependence of the different pa- rameters on the polishing alumina concentration presented in Figures 2-4 (see Table III). From a purely mathematical point of view, it is therefore no surprise that there is a close relationship between other parameter combinations given in the same table. A particularly striking feature is that the values for the cleaning effect correlate equally well with dentin abrasion and enamel abrasion. In order to determine how the parameters change if the polishing alumina is mixed with other cleaning agents, test product VIII was analyzed. It consisted of a toothpaste based on amorphous silica as the cleaning agent (test product VII) with 1% polishing alumina added to it. As the measured values for test product VII given in Table IV show, its composition is such that its scratching and polishing values are especially low so that the changes caused by the addition of polishing alumina can be easily identified.

218 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 100- 90- 80- 70- 60 -!- -!- -!- -!- -!- 50 0 2 3 4 5 6 7 8 9 10 polishing alumina (%) Figure 2. Polishing values (PV) of test products I-VI. 200- _ 160- 120- 80- 40 REA + + + RDA 0 I ! I I I I I I I i 0 2 4 6 8 10 polishing alumina (%) Figure 3. Radioactive dentin abrasion (RDA) and radioactive enamel abrasion (REA) of test products I-VI.