Enamel sample preparation for AFM: Influence on roughness and morphology

Area of Science:

• Biomaterials Science
• Dental Research
• Surface Science

Background:

• Human dental enamel prisms range from 3 to 6 µm in diameter.
• Ultrastructural analysis of enamel surface treatments is crucial for in vitro studies.
• Sample preparation methods like grinding and polishing are common but may introduce artifacts.

Purpose of the Study:

• To evaluate the influence of different dental enamel preparation methods on ultrastructural observation artifacts.
• To compare the effects of no preparation, diamond paste polishing, silicon carbide grinding, and combined grinding/polishing on enamel surfaces.
• To assess the suitability of Atomic Force Microscopy (AFM) for analyzing prepared enamel surfaces.

Main Methods:

• Four groups of dental enamel samples (n=10) were prepared: no preparation, diamond paste polishing, silicon carbide grinding, and grinding with polishing.
• Surface morphology was observed using Peak-Force Tapping mode Atomic Force Microscopy (AFM).
• Samples were subsequently acid-etched with 37% phosphoric acid, rinsed, and dried for further analysis.

Main Results:

• Grinding and polishing exposed inner enamel surfaces, revealing a less mineralized layer with scratches.
• Prepared surfaces showed increased susceptibility to subsequent treatments and morphological alterations.
• Native enamel provided more reliable information on surface and roughness changes relevant to clinical applications.

Conclusions:

• Native enamel samples are preferable for investigating treatment effects on enamel surfaces when feasible.
• Grinding and polishing can create artifacts, obscuring true surface morphology and treatment interactions.
• Phosphoric acid etching can aid in visualizing the prismatic arrangement after surface preparation.