title: Resin bonding to dentin irradiated by high repetition rate Er:YAG laser.
abstract: OBJECTIVE
  This study evaluated the influence of laser irradiation with a high pulse repetition rate on dentin bonding.
  
  
  BACKGROUND
  Although resin bonding to erbium:yttrium-aluminium-garnet (Er:YAG) laserirradiated dentin has frequently been investigated, the effects of a high pulse repetition rate have not yet been sufficiently investigated.
  
  
  METHODS
  Four groups treated under different laser conditions were evaluated in this study: 100 mJ/pulse-10 pulses per second [pps], 50 mJ/pulse-20 pps, 33 mJ/pulse-30 pps, and the unlased condition as a control. The total energy used to irradiate each group was adjusted to 1.0 W. After bovine dentin specimens were irradiated by an Er:YAG laser, acid conditioners (10% citric acid/3% ferric chloride) were applied to the lased surface. Thereafter, a PMMA rod was bonded to the lased dentin using 4- META/MMA-TBB resin, and mini-dumbbell-shaped specimens were prepared. These specimens were then tested under tensile mode and fractured surfaces were observed under scanning electron microscopy (SEM).
  
  
  RESULTS
  The bond strength of the unlased control was significantly higher than those of the three lased groups. Among the three lased groups, irradiation with higher output energy and lower pulse repetition rate tended to affect the higher bond strength. Upon SEM observation of the fractured surface, the lased groups showed the mixture of failure in the hybrid layer in almost part. There was no significant difference among the three lased groups.
  
  
  CONCLUSIONS
  It can be concluded from the results of this study that a higher pulse repetition rate is not effective for resin bonding to laser-irradiated dentin.
authors.affiliation: Department of Operative Dentistry, Tokyo Dental College, Chiba, Japan.
authors.forename: Koya
authors.initials: K
authors.lastname: Aizawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kameyama
authors.forename: Junji
authors.initials: J
authors.lastname: Kato
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Amagai
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Takase
authors.forename: Eiji
authors.initials: E
authors.lastname: Kawada
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Oda
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Hirai
mesh_terms: D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000528:radiation effects*; D001840:Dental Bonding; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure; D004871:Erbium; D007834:Lasers; D008855:Microscopy, Electron, Scanning; D009354:Neodymium; D015019:Yttrium
chemical_list: D003188:Composite Resins; D009354:Neodymium; D015019:Yttrium; D004871:Erbium