Brushing your teeth effectively lowers your chances of getting a host of chronic diseases, as well as keeping your teeth and gums healthy. But the majority of us are doing it wrong.

In Sweden, one study found as few as one in 10 people practice the best brushing technique.

The British health insurer Bupa found that almost half of respondents did not know how to brush their teeth properly in a survey of 2,000 people in the UK.

So what exactly are most of us getting wrong, and how can we change our routine to make sure we brush our teeth effectively? Here's how to properly brush your teeth, according to experts.

"Lots of patients understand that what they need to do is remove food remnants," says Josefine Hirschfeld, associate professor and specialist in restorative dentistry at the University of Birmingham in the UK.

"That is only partially true. It's much more important to remove bacteria from the teeth."

These bacteria and other microorganisms grow inside everyone's mouth, and form a claggy biofilm commonly known as dental plaque.

It is made up of around 700 different species of bacteria, the second-greatest diversity in the human body after the gut, as well as a host of fungi and viruses.

"They are living in the sticky film stuck to the teeth and also to the soft tissues," says Hirschfeld. "This sticky film can't be easily rinsed off – it really needs to be manually cleaned."

The most important place to remove it from is not in fact the teeth, but the gumline.

This is where microbes are best able to infiltrate the gum tissue and cause inflammation, and eventually conditions such as periodontitis.

In fact, "brushing your teeth" is something of a misnomer. "Think of brushing your gumline, rather than the teeth themselves," says Hirschfeld. "The teeth will then be brushed automatically."

Brushing too hard, especially with a firmer-bristled brush, can cause trauma to the gums.

Small tears in the soft tissue caused by overzealous brushing are an opportunity for bacteria to enter the bloodstream.

And grating the brush's bristles over the enamel can wear miniscule grooves in the tooth, which add up to significant erosion over time.

There are some toothbrushes and toothpastes on the market that will literally "brush the teeth away", says Hirschfeld.

Highly abrasive toothpastes, which are often marked as "whitening", and hard-bristled brushes are notorious for this, particularly when used together.

Is it better to brush your teeth before or after breakfast? It depends on what you've had to eat.

Acidic food and drink – such as citrus fruit, fruit juice and coffee – would be a reason to brush before rather than after breakfast.

Acids attack the enamel layer of the teeth and soften it for a certain amount of time.

This strips out some of the key components of the enamel – calcium and phosphate – though these are replaced over a period of hours by minerals in the saliva.

But if you don't wait for that self-repair to happen, then this eroded surface will become very susceptible to just being brushed off.

More important than the breakfast question is the evening brush, which also has a simpler answer: it should always happen last thing before bed.

"Your saliva is your natural protective mechanism," says Nigel Carter, chief executive of the Oral Health Foundation in the UK, inhibiting bacterial growth and tooth decay.

"The saliva flow reduces overnight, so that's why it's very important that all the plaque is cleared away before you sleep."

Spitting out toothpaste when you're finished but refraining from rinsing helps the fluoride to hang around the teeth longer, for additional protection.