Stiffness Grade Survey of American Manufactured Toothbrushes

Objective: A survey was conducted of American manufactured toothbrushes to determine whether stiffness category labeling complied with ISO 8627 guidelines. ISO 8627 is an International Standard used to determine the stiffness of the tufted area, or bristles, of toothbrushes. The stiffness grade value (G) that is determined corresponds to one of three stiffness categories: soft (G less than 6), medium (G greater than 6, less than 9), and hard (G greater than 8). Methods: The toothbrush samples tested in this study were either supplied directly from the manufacturer (in retail packaging) or were purchased in a store. ISO 8627 tests were performed on 77 different toothbrush models from 8 different manufacturers, using 5 examples of each model, for a total of 395 toothbrushes. A Toothbrush Stiffness Testing Apparatus (Sabri Dental Enterprises, Downers Grove, IL) was employed to determine stiffness grades. The device can slide a toothbrush at a velocity of 18 mm/s or higher in a direction parallel to the brushing surface, and it is capable of measuring forces of up to 20 N (± 0.05 N). Each example was conditioned in water at 23 ± 4 °C for 90 seconds, and within 3 minutes of removal from the water, was mounted on the test apparatus and testing commenced. The G values thus determined were then evaluated for statistical differences from those indicated on product labeling. Results: Stiffness grade results achieved show some inconsistencies between ISO 8627 recommendations and current stiffness category labeling. Conclusion: The toothbrush stiffness categorizations of the American manufacturers surveyed do not consistently follow ISO 8627 guidelines.