Tooth enamel seems to be like bone; however, it’s not living tissue. This outer layer of the tooth which encases and protects other tissue inside the tooth forms once we are young, and as soon as teeth are developed, it has no natural capability to self-repair or regrows.
Fortunately, the mineralization process that produces tooth enamel creates an extremely tough substance that’s harder than steel, and the new study shows that a never-before-seen mechanism that helps make its exceptional resilience possible.
These extremely tiny crystals are made from a type of calcium apatite known as hydroxyapatite. The identical mineral substance is discovered in the teeth of other creatures too, and the crystals are small, measuring less than one-thousandth the thickness of a human hair.
They’re so small in fact; it has been challenging to get a great look at them before now.
While using the PIC mapping technique on human teeth, the researchers noticed that the hydroxyapatite nanocrystals were not located in the form that researchers had assumed.
The crystals In enamel are bundled into formations known as rods and inner rods; however, the team recognized a continuous change in the crystal orientations between adjacent nanocrystals that weren’t anticipated, with misorientations ranging between 1 and 30 degrees in adjacent crystals.
As for how such non-alignment exists, Gilbert and colleagues think they have got an answer.
It would be difficult to test this hypothesis in human teeth in actual life; however, molecular dynamics simulations carried out by the team support the concept.
In a computer model designed to simulate how cracking might unfold by enamel’s crystal structure via pressure, the cracking propagated more rapidly by crystal networks that did not resemble human teeth misorientations (of 1 to 30 degrees).
The researchers, therefore, recommend that this range of nanocrystal misorientation may signify a sweet spot in crack deflection, and one in which “enamel’s long evolutionary history” might have selected for, the team says.