Influence of different acid conditioners on the tensile bond strength of 4-META/MMA-TBB resin to Er:YAG laser-irradiated bovine dentin.
OBJECTIVE
This study evaluated the effect of acid conditioners on resin bonding to dentin following irradiation with an Er:YAG laser and investigated the characteristics of resin bonding to the laser-treated dentin.


METHODS
Extracted bovine teeth were cervically sectioned to expose a dentin surface. After polishing, the dentin was irradiated with an Er:YAG laser. Aqueous solutions of 10% citric acid (10-0) or 10% citric acid/3% ferric chloride (10-3) were then applied to the laser-treated surface as acid conditioners. After the acid treatment, a PMMA rod was bonded to the irradiated dentin using 4-META/MMA-TBB resin, and miniaturized dumbbell-shaped bonded specimens were prepared. These specimens were subjected to tensile testing, and fractured surfaces were observed with field-emission scanning electron microscopy (FE-SEM) to determine the mode of fracture. Additionally, the resin-dentin interfaces were observed under FE-SEM.


RESULTS
The tensile bond strength of acid-conditioned bonded specimens was lower than that of specimens not subjected to acid treatment (11.1 MPa) in the laser-irradiated group. No significant difference was observed between 10-0 and 10-3 treatments. 10-3 treatment yielded the highest bond strength (24.6 MPa) in the nonirradiated group, as opposed to only 7.7 MPa in the laser-treated group. Cohesive failure in the dentin was observed in almost all specimens in the irradiated group. Furthermore, a 10- to 30-micron-thick resin-penetrated layer was observed at the interface between the dentin and resin.


CONCLUSIONS
These results suggest that the effect of acid conditioners on resin bonding to dentin differs according to whether the dentin has been laser irradiated or not.
Kameyama
A
A
Third Department of Conservative Dentistry, Tokyo Dental College, Chiba 261-8502, Japan. kameyama@tdc.ac.jp
Kawada
E
E
Takizawa
M
M
Oda
Y
Y
Hirai
Y
Y
D000134:Acid Etching, Dental / Q000379:methods*; D000180:Acrylic Resins / Q000737:chemistry / Q000528:radiation effects; D000538:Aluminum Silicates; D000704:Analysis of Variance; D000818:Animals; D001896:Boron Compounds / Q000737:chemistry / Q000528:radiation effects; D002417:Cattle; D002712:Chlorides; D019343:Citric Acid / Q000008:administration & dosage; D001840:Dental Bonding; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004871:Erbium; D005290:Ferric Compounds / Q000008:administration & dosage; D007834:Lasers; D008689:Methacrylates / Q000737:chemistry*; D020366:Methylmethacrylate / Q000737:chemistry / Q000528:radiation effects; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000008:administration & dosage; D019904:Polymethyl Methacrylate / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013223:Statistics as Topic; D013499:Surface Properties; D013718:Tensile Strength; D015019:Yttrium
D000180:Acrylic Resins; D000538:Aluminum Silicates; D001896:Boron Compounds; D002712:Chlorides; D017220:Dentin-Bonding Agents; D005290:Ferric Compounds; D008689:Methacrylates; D010756:Phosphoric Acids; D019279:Resin Cements; C084543:Super Bond D-Liner; C009523:tri-n-butylborane; D020366:Methylmethacrylate; D019343:Citric Acid; D015019:Yttrium; D004871:Erbium; C031172:4-META resin; D019904:Polymethyl Methacrylate; C024555:ferric chloride