Effect of Er:YAG laser treatment on the microstructure of the dentin/adhesive interface after acid-base challenge.
OBJECTIVE
The aim of this study was to evaluate the effect of Er:YAG laser ablation on the microstructure of the dentin/adhesive interface after acid-base challenge in vitro.


METHODS
Thirty-two extracted third molars were used. One pair of disk-shaped specimens was obtained from the midcoronal dentin of each tooth. One surface in each pair was subjected to Er:YAG laser irradiation, while the other was ground using 600-grit SiC abrasive paper. The specimens were assigned to 4 groups with 8 pairs in each group. A self-etching primer (Clearfil SE-Bond), a bonding adhesive (Clearfil SE-Bond), and a photocuring composite (Clearfil AP-X) were applied accordingto manufacturer's instructionsto create dentin-resin "sandwiches" of each pair, except in group IV, where no primer was applied. The specimens were stored in demineralizing solution for 20 min in groups I and IV, 60 min in group II, and 120 min in group III. After immersion in 5% NaOCl, all the specimens were polished and argon-ion etched. Finally, the interfaces between the dentin and bonding agent were observed under a scanning electron microscope.


RESULTS
All specimens in groups I to III showed an acid-base resistant zone, except those of group IV, which debonded completely. A statistically significant difference was found in the thickness of the acid-base resistant zone between group I vs groups II and III for both abraded and Er:YAG-irradiated surfaces. There was no statistically significant difference in the thickness of the acid-base resistant zone between groups II and III for both conventionally prepared and Er:YAG-irradiated surfaces.


CONCLUSIONS
The existence of an acid-base resistant zone followingthe application of the SE Bond system on both abraded and Er:YAG-lased human dentin, regardless of the acid-base challenge duration, was confirmed.
Bakry
Ahmed Samir
AS
Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. bakry.ope@tmd.ac.jp
Sadr
Alireza
A
Inoue
Go
G
Otsuki
Masayuki
M
Tagami
Junji
J
D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D001840:Dental Bonding; D017005:Dental Debonding; D045662:Dental Etching / Q000379:methods; D003775:Dental Polishing; D003804:Dentin / Q000601:surgery / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D053685:Laser Therapy; D054020:Lasers, Gas; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry; D012973:Sodium Hypochlorite / Q000737:chemistry; D013499:Surface Properties; D017001:Tooth Demineralization / Q000473:pathology / Q000601:surgery
D017554:Carbon Compounds, Inorganic; C112828:Clearfil AP-X; C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; D017655:Silicon Compounds; D012973:Sodium Hypochlorite; C022088:silicon carbide