The SEM electron-mirror effect in human tooth and synthetic hydroxyapatite samples

Area of Science:

• Materials Science
• Surface Science
• Microscopy

Background:

• The electron-mirror effect (EME) is sensitive to sample properties.
• Human teeth (dentin, enamel) and hydroxyapatite are relevant biomaterials.
• Polyethylene terephthalate (PET) and epoxy resin serve as EME-producing benchmarks.

Purpose of the Study:

• Investigate the EME behavior of dentin, enamel, and synthetic hydroxyapatite.
• Analyze the influence of calcination on EME.
• Determine the dielectric constant of dentin and PET.

Main Methods:

• Scanning electron microscopy with electron-mirror effect (EME) analysis.
• Ex situ calcination treatments at 700°C and 1,200°C.
• Dielectric constant calculation based on EME data.

Main Results:

• Dentin exhibited a distorted EME, while enamel and hydroxyapatite did not initially.
• Calcination above 700°C induced EME in all samples, but with significant image deformation.
• The charge-edge effect was identified as the cause of post-calcination EME deformation.
• Calculated dielectric constants: 8.7 for dentin and 3.8 for PET.

Conclusions:

• Dentin's EME characteristics differ from enamel and synthetic hydroxyapatite.
• Calcination significantly alters the EME response of teeth and hydroxyapatite.
• The charge-edge effect is crucial for understanding EME in thermally treated samples.