Strength of Integrated Dental-floss and Handles in Hong Kong

Abstract

Objectives: The purpose of this study was to compare the strength of dental flosses and their handles in Hong Kong market. Methods: Sixteen models (price from US$0.01-0.26/ea) of integrated dental floss and handles were purchased in Hong Kong supermarkets. Static test with reference to ISO 28158 was used for randomly picked 15 samples from each model. Each sample was subjected into water at 37°C for 90 seconds before fixed it with the clamping device (modified from ISO 28158 in order to fit for all the design and shapes of the handles) to the vice, and then connected the metal static weight 1kg (10N) to the hook. After couting for 10s, distance of displacement (in mm) was measured by caliper. The passing criteria are: (1) withstand the static load of 10N for 10s without a breakage of the floss and handles, (2) loading point does not displace more than 10mm in the direction of the loading (3) 12 out of 15 specimens pass the test. Results: Whilst 14 models passed all the criteria, 2 out of 16 models (12.5%) could not pass the test, and one handle was broken during the test. This poses a safety concern for these products. The fail model either contains activated carbon, or the handle is too weak, and their average distance of displacement were 10.6mm (46.7% failure for static load) and 12.9mm (100% failure). Conclusions: The design of the floss and handle matters a lot in the safety. More stringent passing criteria should be adopted.