Dentin diffusion of HEMA released from etch-and-rinse and self-etch bonding systems

Area of Science:

• Dental Materials Science
• Biomaterials Science
• Polymer Chemistry

Background:

• 2-hydroxyethyl methacrylate (HEMA) is a common monomer in dental adhesives.
• Understanding HEMA diffusion through dentin is crucial for assessing potential pulpal effects.
• Remaining dentin thickness (RDT) significantly influences the diffusion of substances through dentin.

Purpose of the Study:

• To quantify the diffusion of HEMA from various dental bonding systems (BS) through dentin.
• To evaluate the impact of remaining dentin thickness (RDT) on HEMA diffusion.
• To compare HEMA diffusion between phosphoric acid-etched and self-etch bonding systems.

Main Methods:

• In vitro study using human dentin discs with RDT of 0.5 mm and 0.25 mm.
• Application of different bonding systems, with and without prior phosphoric acid etching.
• Detection of HEMA using gas chromatography/mass spectrometry in artificial pulp chambers.

Main Results:

• Higher HEMA concentrations were detected with thinner RDT (0.25 mm) compared to thicker RDT (0.5 mm).
• OptiBond FL with 0.25 mm RDT showed the highest mean HEMA concentration (13.3 µg).
• Phosphoric acid etching significantly increased HEMA diffusion compared to self-etch bonding systems.

Conclusions:

• Dentin thickness is a critical factor in HEMA diffusion from dental bonding systems.
• Phosphoric acid etching enhances HEMA diffusion, posing a higher risk in deep cavities.
• Self-etch bonding systems are recommended over phosphoric acid-etched systems for deep cavity preparations to minimize HEMA diffusion.