Thomas Thornton, the President of Thornton International, invented the interproximal toothbrush in the 1970s and has been selling his product, and modernised versions of it, across the United States ever since.
An interproximal toothbrush is essentially a specially designed piece of dental floss, which is thicker and stronger in the middle, with a stiff piece of nylon at either end allowing it to be fed through gaps and then used more like a toothbrush.
Dental floss like this is especially useful for people who have braces, implants or bridges as normal dental floss can often be too soft to effectively remove food and plaque from these tight gaps with potentially sharp edges. However, the three Thornton dental floss products are ideal for keeping these pieces of oral equipment clean, once you have got used to using the interproximal toothbrush.