by Rob Waugh
Many people brush more than the recommended number of times per day – especially after a rich meal.
Brushing within half an hour of eating a meal or drinking a cup of coffee could ensure your teeth suffer worse damage.
After drinking fizzy or acidic drinks, the acid burns into the enamel of your teeth – and the layer below the enamel, called 'dentin'.
Brushing at the 'wrong' time – particularly within 20 minutes of finishing a meal – can drive the acid deeper into your teeth, corroding them far faster than they would have rotted by themselves.
'With brushing, you could actually push the acid deeper into the enamel and the dentin,' says Dr Howard R. Gamble, president of the Academy of General Dentistry in an interview with the New York Times.
Research has shown that teeth corrode faster if they are brushed in the half hour after an acidic soft drink, which 'stripped' them – demineralising them.
Volunteers wore human dentin samples in their mouths, and tested different brushing regimens.
Brushing in the 20 minutes after a soft drink damaged teeth noticeably – although anyone who's just eaten a spicy meal might be relieved to know that waiting an hour seems to be enough to avoid the negative effects.
'However, after intra-oral periods of 30 and 60 min, wear was not significantly higher than in unbrushed controls,' say the researchers.
'It is concluded that for protection of dentin surfaces at least 30 min should elapse before toothbrushing after an erosive attack.'