The effect varied scanning electron microscopy desiccation techniques has on demineralized dentin

Area of Science:

• Biomaterials Science
• Dental Ultrastructure
• Surface Chemistry

Background:

• Understanding dentin surface modification is crucial for dental restorative procedures.
• Scanning electron microscopy (SEM) is vital for visualizing ultrastructural changes.
• Desiccation techniques can significantly influence SEM observations of biological samples.

Purpose of the Study:

• To evaluate the ultrastructural effects of ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) on human dentin surfaces.
• To assess the impact of two SEM desiccation methods (critical point drying vs. air-drying) on the collagen surface.

Main Methods:

• Proximal root surfaces of human teeth were prepared to expose dentin.
• Dentin surfaces were treated with 30% CA or 24% EDTA solutions via rubbing application.
• Specimens underwent either critical point drying (CO2) or air-drying (tetramethylsilane) before SEM analysis.

Main Results:

• Critical point drying revealed tufted collagen fibrils, more pronounced with CA than EDTA, partially obscuring dentin tubules.
• Air-drying resulted in a flattened collagen monolayer without a meshwork, showing fibril collapse and coalescence.
• EDTA-treated surfaces exhibited unique discrete fibril 'sprigs' after critical point drying.

Conclusions:

• Rubbing EDTA on dentin creates a tufted fibril surface, comparable to CA.
• Air-drying desiccation causes significant distortion and collapse of the collagen matrix, compromising ultrastructural integrity for SEM.
• Critical point drying is superior for preserving the native ultrastructure of treated dentin surfaces for SEM analysis.