First they tried to grow a batch of bacteria responsible for strep throat on new toothbrushes and found that the germs did indeed grow and thrive on the bristles for about 48 hours. Next, they investigated whether the bacteria could be transferred from the mouths of children with strep throat and then grow on the brushes.
In the study, 14 patients diagnosed with strep throat, 13 patients with sore throats without strep, and 27 healthy young people brushed their teeth for one minute with a new toothbrush. The brushes were then taken to a lab to test for bacteria growth.
The scientists found strep throat bacteria on only one toothbrush, and surprisingly that was one that had been used by a patient without strep throat. The other study toothbrushes all failed to grow the strep bacteria, while they did grow plenty of other common bacteria found in the mouth.
"This study supports that it is probably unnecessary to throw away your toothbrush after a diagnosis of strep throat," said co-author Dr. Judith L. Rowen in a statement.
Still, the American Dental Association recommends tossing your toothbrush every three to four months -- and even more frequently if the bristles become frayed or you're sick. WebMD also reports that while there is some evidence that toothbrush sanitizers can kill germs, there is no real proof that they can keep you from getting sick.