title: Resin-dentin bonding interface after photochemical surface treatment.
abstract: OBJECTIVE
  The aim of this study is to elucidate the structure of the resin-dentin interface formed by photochemical dentin treatment using an argon fluoride (ArF) excimer laser.
  
  
  BACKGROUND
  The ArF excimer laser processes material by photochemical reaction without generating heat, while also providing surface conditioning that enhances material adhesion. In the case of bonding between resin and dentin, we demonstrated in a previous study that laser etching using an ArF excimer laser produced bonding strength comparable to that of the traditional bonding process; however, conditions of the bonding interface have not been fully investigated.
  
  
  METHODS
  A dentin surface was irradiated in air with an ArF excimer laser followed by bonding treatment. Cross sections were observed under light microscope, transmission electron microscope (TEM), and scanning electron microscope, then analyzed using an energy dispersive X-ray spectroscope (EDS): EDS line profiles of the elements C, O, Si, Cl, P, and Ca at the resin-dentin interface were obtained.
  
  
  RESULTS
  The density of C in resin decreased as it approached the interface, reaching its lowest level within the dentin at a depth of 2 μm from the resin-dentin interface on EDS. There was no hybrid layer observed at the interface on TEM. Therefore, it was suggested that the resin monomer infiltrated into the microspaces produced on the dentin surface by laser abrasion.
  
  
  CONCLUSIONS
  The monomer infiltration without hybrid layer is thought to be the adhesion mechanism after laser etching. Therefore, the photochemical processes at the bonding interface achieved using the ArF excimer laser has great potential to be developed into a new bonding system in dentistry.
authors.affiliation: 1 Oral Diagnosis and General Dentistry, Dental Hospital, Tokyo Medical and Dental University , Tokyo, Japan .
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Tonami
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Sano
authors.forename: Shizuko
authors.initials: S
authors.lastname: Ichinose
authors.forename: Kouji
authors.initials: K
authors.lastname: Araki
mesh_terms: D001840:Dental Bonding; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D066298:In Vitro Techniques; D054018:Lasers, Excimer; D008854:Microscopy, Electron; D055668:Photochemical Processes; D019279:Resin Cements / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties
chemical_list: D017220:Dentin-Bonding Agents; D019279:Resin Cements