Fluoride-Releasing Self-Etch Adhesives Create Thick ABRZ at the Interface

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Nanotechnology in Dentistry

Background:

• Fluoride-releasing adhesive systems aim to enhance composite restoration longevity by promoting mineralization of surrounding tooth structure.
• The formation of an
• acid-base resistant zone
• (ABRZ) beneath the hybrid layer has been observed with self-etch adhesives.

Purpose of the Study:

• To investigate the effect of fluoride release from self-etch adhesives on the formation and properties of the ABRZ.
• To determine the relationship between fluoride concentration and the quality of the ABRZ.
• To elucidate the chemical mechanisms underlying fluoride's protective effect on dentin.

Main Methods:

• Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for morphological analysis of the ABRZ.
• Digital image analysis (region of interest mode) for quantitative assessment of acid resistance.
• X-ray absorption fine structure (XAFS) analysis to identify fluoride-induced chemical changes in dentin.

Main Results:

• Fluoride-releasing self-etch adhesives formed a thicker and more resistant ABRZ compared to non-fluoride-releasing systems.
• The area and quality of the ABRZ were influenced by the concentration of fluoride released from the adhesive resin.
• XAFS analysis revealed the formation of fluorapatite and CaF₂-like structures on dentin treated with varying fluoride concentrations.

Conclusions:

• Fluoride release from adhesives is crucial for forming a high-quality ABRZ, enhancing dentin/enamel bond durability.
• A potential threshold concentration of fluoride exists for optimal ABRZ formation.
• NaF effectively improves bond durability and ABRZ quality, contributing to improved clinical success of dental restorations.