Holed up in Newgate prison on a rioting charge, William Addis, a tanner by trade, decided to do something useful during his time inside. But it was 1770 - matchstick modelling was prohibitively expensive, and Open University courses hadn't been invented. Then again, thought Mr Addis with a carious grin, neither had the toothbrush.
Retrieving a piece of bone from his dinner plate, he got hold of some hairs from the tail of a cow, fastened them on and thereby fashioned the forerunner of the modern toothbrush. It was a defining moment in the history of oral hygiene, and on his release from prison Mr Addis set up a brush-making business that remained in his family until 1996.
Mr Addis's invention coincided with the first false teeth, made in the same year, proving that his preventative device had come too late for many people. Dental care was a rotten business in those days and Elizabethans would clean their teeth using cloths dipped in salt or sulphur oil, or toothpicks made from goose feathers.
Ancient Egyptians took pride in their pearly whites and were often buried with their frayed twig toothbrushes, similar to those still plucked from arak or neem trees, each known in parts of Africa and Asia as the "toothbrush tree". By the 16th century, the Chinese were using boar's hair for bristles set in bamboo handles and French dentists were recommending tubular toothbrushes made "in the manner of a paintbrush".
When nylon was invented in 1938, it was immediately put to use as a replacement for unhygienic boar's hair. Improved brush-making methods, increased production and health education soon made the toothbrush the first item in anyone's overnight bag.
Tooth decay used to be an upper-class disease, because such people were the only ones who could afford to eat sugar and rich foods. But today we can all afford to eat badly, and plaque - the sticky film of bacteria that causes decay and gum disease - is now being attacked with ever more ingenious implements.
Only three-quarters of women and just over half of men bother to do so, but your recommended twice-daily brushing can now be carried out in style. Ergonomic handles, non-slip grips, flexible angled heads and multi-textured bristles have turned toothbrushes into serious design items. They have even gone electric. Too late, alas, for one Dr Scott, who patented the first such device in 1880, but never made a penny from his invention - perhaps because of the guarantee that every one was "permanently charged with electro-magnetic current". Shocking.