albicans) which have infected the tooth structure,' said co-presenter Gary Hack, associate professor at the Dental School.

For the sake of humouring his students, Hack said: 'I call them tooth worms and I'm sticking to it.' The aim of the Maryland study was to investigate the structures with scanning electron imagery and different specimen preparation techniques.

The researchers' observations raised new questions in the controversy over nature of the strange structures. For example, they found two of the cylinder structures within a single tubule, a discovery that challenges the hypothesis that the structures are cellular extensions.

Whereas the majority of the structures appear to be hollow and devoid of any content, a number of these structures appear to be solid, said an U-M release.

These findings were presented at the annual meeting of the Microscopy Society of America in Richmond.