Resin-dentin bonding interface after photochemical surface treatment.

Area of Science:

• Dental materials science
• Biomaterials engineering
• Photochemistry

Background:

• Argon fluoride (ArF) excimer laser offers photochemical material processing without heat, enhancing adhesion.
• Previous studies showed ArF laser etching yields bonding strength comparable to traditional methods.
• The specific structure of the resin-dentin interface formed by this laser treatment remained uninvestigated.

Purpose of the Study:

• To elucidate the structure of the resin-dentin interface.
• To investigate the interface formed by photochemical dentin treatment using an ArF excimer laser.

Main Methods:

• Dentin surfaces were irradiated with an ArF excimer laser in air, followed by bonding.
• Microscopic analysis included light microscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM).
• Energy dispersive X-ray spectroscopy (EDS) was used for elemental analysis (C, O, Si, Cl, P, Ca) at the interface.

Main Results:

• EDS revealed a decrease in carbon density in the resin approaching the interface, reaching a minimum 2 μm into the dentin.
• TEM analysis showed no hybrid layer formation at the resin-dentin interface.
• Resin monomer infiltration into laser-created microspaces on the dentin surface was suggested.

Conclusions:

• Monomer infiltration into laser-etched dentin, without a hybrid layer, is proposed as the adhesion mechanism.
• The photochemical processes at the bonding interface using ArF excimer laser hold potential for novel dental bonding systems.