When people get braces on their teeth, the reason is usually to improve appearance.
But scientists have found that having straight teeth improves our sense of balance and posture.
People with 'overbites' or 'underbites', crowded teeth or wonky teeth - known to dentists and orthodontists under the general heading of malocclusions - are less steady on their feet, the researchers discovered.
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The theory that a bad bite may affect the whole body was tested on ten physically active people. The Spanish researchers, in a paper in Neuroscience Letters, said: "A remarkable finding of the study was that dental occlusion significantly influenced the balance control of the subjects."
Having a bad bite meant worse balance, they found, particularly when the subjects were tired.
The researchers said the link between bad bite and bad posture was not obvious in everyday conditions, but came into play with conditions that worsen the body's stability - such as obesity.
It may also have an effect on athletes, playing a key role in how well they perform, as well as making them more likely to get strains when they become more tired.
The link may be because the main nerve responsible for chewing - the trigeminal - is closely linked to the vestibular nucleus, the part of the brain responsible for balance control, as are our neck and jaw muscles.
Lead researcher Sonia Julia Sanchez said: "It would be helpful for both the general population and athletes to consider correcting dental occlusions to improve postural control and thus prevent possible falls and instability due to a lack of motor system response."