Comparison between radiotracer and surface profile methods for the determination of dentifrice abrasivity

This study compared the traditional radiotracer method (Rt) for determination of dentifrice abrasivity to the recently introduced surface profile (Sp) method (ISO 11609). Specimens from human root dentin were prepared for each method and randomly assigned to 8 dentifrice/abrasive groups (n=8), of wide abrasivity range. Aqueous dentifrice slurries or abrasive suspensions were used to brush specimens in a toothbrushing machine. Two independent studies (Rt, Sp) were carried out. For Rt, the specimen preparation, study design, analysis and calculation of the dentifrice abrasive level (RDA) followed the ISO 11609/Annex-A guidelines. Similarly for Sp, the ISO 11609/Annex-B recommendations were followed, except by the number of brushing strokes, which was pre-determined to be 2000 strokes. RDA data were analyzed using ANOVA and Tukey tests (α=0.05). The correlation between methods was also investigated. Overall, higher variation and RDA values were observed for Sp compared to Rt. While good correlation was found between methods (R2=0.841), group ranking was dissimilar and better statistical differentiation among groups was observed in Rt. The Rt method showed to be a more standardized and robust method compared to Sp for the determination of RDA values of dentifrices/abrasives. Sp needs further development before being considered as an equivalent method to Rt.