Thermal decomposition of human tooth enamel

Area of Science:

• Materials Science
• Biomineralization
• Crystallography

Background:

• Human tooth enamel (TE) is a biomineral with a complex structure.
• Understanding the thermal behavior of TE components is crucial for various applications.
• Previous studies recognized some thermal degradation pathways but lacked detailed insights.

Purpose of the Study:

• To investigate the thermal decomposition of human tooth enamel (TE).
• To quantify the loss and transformation of key components like carbonate, hydroxyl, and water.
• To correlate these changes with alterations in the enamel's crystal lattice structure.

Main Methods:

• Heating TE in N2 or vacuum from 25-1000°C.
• Utilizing quantitative infrared spectroscopy.
• Employing lattice parameter and thermogravimetric analysis.

Main Results:

• Carbonate loss begins at lower temperatures (around 100°C) than previously thought.
• Structural hydroxyl content increases significantly up to 400°C.
• A sharp loss of structural water around 250-300°C correlates with lattice parameter contraction and reordering.

Conclusions:

• Early carbonate loss has implications for in vitro and in vivo treatments.
• Carbonate migration between A and B sites suggests interconnectedness relevant to biological conditions.
• Structural water plays a key role in the lattice expansion of TE compared to pure hydroxyapatite.