Dakar — Brush your teeth every day, dentists say. In Africa, that can mean keeping your toothbrush in your mouth all day long.
Across the continent south of the Sahara, many people go about their daily business with a small stick or twig protruding from their mouth, which they chew or use to scrub their teeth.
Cut from wild trees and shrubs in the bush, this is the African toothbrush. Its users swear it is much more natural, effective - and cheaper - than the prettily packaged but pricey dental products on sale in pharmacies and supermarkets.
"It cleans your teeth more than plastic brushes, with the liquid that comes out of the wood," said Mr Marcelino Diatta, a stick twitching from his mouth as he sought handouts from foreigners in downtown Dakar.
In Senegal, the chewing stick is called "sothiou", which means "to clean" in the local Wolof language. In east Africa, the stick is called "mswaki", the Swahili word for toothbrush.
Their users say the sticks are also medicinal, providing not just dental hygiene but also curing a variety of other ills. Dental experts agree they seem to clean teeth well and some up-market health stores in the United States have been selling chew-sticks as a natural form of dental care.
"It's good for your stomach and your head ... it whitens your teeth and gets rid of bad breath," said Abedis Sauda, a Senegalese street vendor.
Traders in Dakar and other Senegalese cities sell neat bundles of the pencil-sized sticks - usually about six inches long -on the pavement, offering a variety of different types of wood at different prices.
Mr Elimane Diop, 70, dressed in a blue boubou robe and white bonnet, extols the virtues of his wares with all the pride of a salesman for a multinational health care company, explaining the advantages of a new design of brush or type of dental floss.
"This is the Dakhaar ... It cleans really well," said Mr Diop, holding up a slender, knotty twig with a dark brown bark.
Another bush toothbrush, the Werek, is cut from the branches of the gum tree, while the thicker Neep-Neep helps ease toothache. "If you've a bad tooth, it's a medicine," said Mr Diop.
The Cola, cut from a soft, whitish wood, is prized for its sweet taste.
If chewed, most of the twigs fray into finer strands, which have the effect of "flossing" between the teeth, or if rubbed up and down, can scrub tooth enamel clean as well as any brush. But they can taste bitter compared with commercial toothpastes.
"There are several documented studies which suggest that the cleaning sticks are at least as effective as normal toothbrushes and paste in maintaining routine oral health," Christine D. Wu, Professor and Associate Dean for Research at the University of Illinois College of Dentistry, told Reuters.
She said some laboratory studies indicated plants from which some of the sticks in Africa are cut contain protective anti-microbial compounds that act against the bacteria in the mouth which cause tooth decay and gum disease.
"And if these sticks do contain fluoride, as plants do, then this would be beneficial for caries prevention," Wu said, although she stressed much more research needed to be done on the sticks and their use by humans.
The World Health Organisation has encouraged the use of chewing sticks as an alternative source of oral hygiene in poor countries where many cannot afford commercial dental products.
In mostly Muslim Senegal, people say there is religious precedent for the use of the chewing sticks.
In holy Islamic writings known as the Hadith, the Prophet Muhammad recommends their use as part of cleaning rituals that are an essential element of daily prayers.
"For prayers, you have to get really clean, and that includes the teeth," said Diop, an invalid whose left leg is deformed - a childhood injury sustained when a sharp twig pierced his bare foot in the bush and the wound became infected.
Although commercially made toothbrushes from leading international brands are available in Dakar supermarkets and pharmacies, many people say they prefer the chew sticks. "It's better because it's natural. I used to use a brush, but it made my gums bleed," said Allissane Sy, an off-duty police officer, stopping to buy a stick from Diop.
Price helps too. While a manufactured toothbrush can cost upwards of 300 CFA francs (60 cents), a chew-stick costs only 25 or 50 CFA.
Mr Diop said each type of stick had different stories and origins associated with them.
For example, the one named Matou-kel was believed to bring luck. It is named after the tree it is cut from where bush deer - prized in Senegal for their tender tasty venison - like to feed and rest.
Another wood variety, Soumpou, was traditionally used to provide a liquid used to cook a fortifying dish, Laakh, which is made with millet. "It gives energy," Mr Diop said.
But Wu had a word of warning for stick chewers: don't overdo it, as too-vigorous scrubbing can push back the gums, causing gum recession exposing teeth roots to damage and decay.