Studies by University of Maryland Dental School researchers' presented at the annual meeting of the Microscopy Society of America in Richmond revealed cylindrical objects extending or ‘growing' out of the natural pores or tubules of teeth.

Inside a human tooth, more than 50,000 such tubules per square millimeter act as channels running from the nerve up through the tooth. They are associated with transporting hot or cold sensitivity to the tooth nerve. [A human hair by comparison is 40 micrometers wide.]

For years, scientists have debated the exact nature of the worm-like structures, which were photographed in clear detail by Ru-Ching Hsia, director of the electron microscope core facility at the School.

Dentists' explanations vary on nature and origin of the structures. "Most say ‘I have no idea.' Others say they are made of bacteria, or minerals, or hyphal branches of yeast cells (C. albicans) which have infected the tooth structure, or perhaps they are a cellular process of the dentinal tubules," said co-presenter Gary Hack, DDS, associate professor in the Dental School. For the sake of humoring his students, Hack says, "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.