Fluorine in shark teeth: its direct atomic-resolution imaging and strengthening function.

Area of Science:

• Materials Science
• Biomineralization
• Electron Microscopy

Background:

• Atomic-resolution imaging of biominerals is difficult due to structural complexity and radiation damage.
• Shark tooth enameloid presents unique challenges for high-resolution imaging.

Purpose of the Study:

• To achieve direct atomic-resolution imaging of shark tooth enameloid.
• To elucidate the complex fluorapatite structure at the atomic level.
• To understand the bonding of fluorine atoms in shark teeth.

Main Methods:

• Aberration-corrected electron microscopy
• Low-dose imaging techniques
• Ab initio calculations

Main Results:

• Successful atomic-resolution imaging of individual atomic columns in shark tooth enameloid.
• Confirmation of a complex fluorapatite structure.
• Evidence of covalent bonding between fluorine and calcium atoms.

Conclusions:

• Direct atomic-resolution imaging is feasible for beam-sensitive biominerals like shark teeth.
• The complex fluorapatite structure and fluorine-calcium bonding contribute to caries resistance.
• Findings have implications for understanding and improving dental health in general.