Human teeth strength same as sharks
Human teeth may not match those of a tiger shark in size or number - but they are just as strong, research has shown.
Scientists made the surprising discovery after comparing the micro-structure of human and shark teeth.
They found that despite the teeth of the top ocean predator being coated with super-tough enamel, they are no stronger than the average human's.
"This is due to the special micro and nanostructure of our teeth," said lead researcher Professor Matthias Epple from the University of Duisburg-Essen in Germany. "The crystals in human teeth have a special arrangement and they are 'glued together' by proteins which stop cracks from running through the whole tooth."
The German team studied the teeth of the shortfin mako and tiger shark, the latter being one of the most dangerous shark species.
Both were found to have similar tooth structures even though they use their teeth in different ways. Mako sharks "tear" into prey while tiger sharks "cut" the flesh of their victims.
Shark teeth have an interior of elastic dentin and an outer layer of hard enamel toughened by the fluorine-based mineral fluoroapatite.
Human enamel is softer, consisting of the mineral hydroxyapatite, which is also present in bones. But because of their structure, the overall strength of human teeth was on a par with that of the shark, the scientists found.
The research, published in the Journal of Structural Biology, could assist the design of stronger and longer-lasting dentures.
"It would be great if, sometime in the future, one could repair teeth with a material which is more natural than today's provisional solutions," said Prof Epple.