A South African matric pupil has won first prize at the Intel International Science and Engineering Fair in Pittsburgh, in the United States, Beeld newspaper reported on Thursday.
Chené Mostert, 17, from Ladysmith High School in KwaZulu-Natal, won the award for her toothbrush sterilising device.
She won R17,000 and an invitation from the American Dental Association to return in December to patent her invention.
"I take part in the Eskom expo for young scientists every year, and earlier in 2012 I was looking for an idea for a project," she said.
"While I was brushing my teeth one night, I noticed the toilet next to the basin, and remembered reading that cold, wet places are ideal breeding places for bacteria.".
She gathered 150 toothbrushes, had them tested and found more than 100 different types of bacteria growing on the bristles.
"I realised there was nothing on the local market for cleaning toothbrushes, so I designed a plastic box with a rotation system in which toothbrushes can be stored and cleaned."
The box contains hydrogen peroxide and four plastic tubes, in which the brushes are placed, and when the user turns a handle, an internal scrubbing brush is activated.
Chené hopes to enrol in medical school in 2013, and wants to eventually become a paediatrician.