Researchers looked at brushing advice given by dental associations across 10 countries, toothbrush and toothpaste companies and in dental textbooks.
Their study, published in the British Dental Journal, found differing recommendations on what method to use when brushing, how often to brush and how long people should brush for.
The experts from University College London (UCL) said there was a "worrying" lack of agreement on advice.
Senior author Aubrey Sheiham, emeritus professor of dental public health at UCL, said: "If people hear one thing from a dental association, another from a toothbrush company and something else from their dentist, no wonder they are confused about how to brush. In this study we found an unacceptably inconsistent array of advice from different sources."
Giving advice on teeth brushing, Prof Sheiham said: "Brush gently with a simple horizontal scrubbing motion, with the brush at a forty-five degree angle to get to the dental plaque.
"To avoid brushing too hard, hold the brush with a pencil grip rather than a fist.
"There is little point in brushing after eating sweets to prevent decay. It takes bacteria from food about two minutes to start producing acid, so if you brush a few minutes after eating sugary foods, the acid will have damaged the enamel."