Field emission SEM comparison of four postfixation drying techniques for human dentin

Area of Science:

• Biomaterials Science
• Dental Materials Science
• Electron Microscopy Sample Preparation

Background:

• Critical-point drying (CPD) is standard for preparing biologic specimens for electron microscopy.
• New developments in dentin bonding have highlighted the need for alternative drying techniques in dentistry.
• This study evaluates HMDS, Peldri II, and air drying as alternatives to CPD for dentin preparation.

Purpose of the Study:

• To compare the effectiveness of hexamethyldisilazane (HMDS), Peldri II, and air drying with critical-point drying (CPD) for preparing demineralized dentin specimens.
• To analyze the ultrastructural preservation of the demineralized dentin matrix using these drying techniques.
• To assess the suitability of alternative drying methods for dentin bonding research.

Main Methods:

• Twenty-four human molar dentin disks were prepared.
• Dentin surfaces were etched with 10% phosphoric acid.
• Specimens were fixed, dehydrated, and dried using CPD, HMDS, Peldri II, or air drying.
• Samples were examined using a field emission scanning electron microscope in longitudinal and cross-sectional views.

Main Results:

• HMDS drying demonstrated superior preservation of the collagen network and microporosity in the intertubular demineralized dentin zone.
• Peldri II drying showed results comparable to CPD.
• Air drying induced artefacts, including surface collapsing and thickening of the denatured collagen layer.

Conclusions:

• HMDS drying is a promising alternative to CPD for preparing demineralized dentin for electron microscopy.
• HMDS drying preserves the structural integrity of the dentin matrix, including collagen and microporosity.
• HMDS drying is easy to perform and suitable for dental research involving dentin bonding.