Reinforcement of dentin in self-etch adhesive technology: a new concept.
OBJECTIVE
Characterize the ultramorphology and secondary caries inhibition potential of different dentin adhesive systems in order to find a satisfactory explanation resist to recurrent caries.


METHODS
Human premolar dentin was treated with one of the two self-etching adhesive systems, Clearfil SE Bond, Clearfil Protect Bond or an acid-etching adhesive system, Single Bond. The bonded interface was exposed to an artificial demineralizing solution (pH 4.5) for 90 min and then 5% sodium hypochlorite for 20 min. Transmission electron microscopic observation was performed at the adhesive-dentin interface. The width of the reinforced zone was measured and data were analyzed with univariate analysis of variance under general linear model. In order to identify type of crystallites in the reinforced zone selected area electron diffraction was performed.


RESULTS
An acid-base resistant zone (ABRZ) was found adjacent to the hybrid layer in the outer lesion front with only Clearfil SE Bond and Clearfil Protect Bond, while Single Bond was devoid of this protective zone. Crystallite arrangement and the ultramorphology were almost similar in the corresponding regions of Clearfil SE Bond and Clearfil Protect Bond. However, thickness of the ABRZ at the mid portion was 1159(+/-41.91)nm in Clearfil protect Bond, which was significantly thicker than that of Clearfil SE Bond (F=514.84, p<0.001). Selected area electron diffraction confirmed the crystallites in the zone as apatite.


CONCLUSIONS
The self-etching adhesive systems created a new reinforced acid resistant dentin under the hybrid layer. Difference in the thickness of the zone expressed a different potential for demineralization inhibition.
Waidyasekera
Kanchana
K
Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. kanchanapgkw@yahoo.com
Nikaido
Toru
T
Weerasinghe
Dinesh S
DS
Ichinose
Shizuko
S
Tagami
Junji
J
D000134:Acid Etching, Dental; D000704:Analysis of Variance; D001641:Bicuspid; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry* / Q000627:therapeutic use; D003731:Dental Caries / Q000517:prevention & control*; D018772:Dental Marginal Adaptation; D019232:Dental Restoration Failure; D003804:Dentin / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry* / Q000627:therapeutic use; D006801:Humans; D016014:Linear Models; D049329:Nanostructures / Q000648:ultrastructure; D019279:Resin Cements / Q000737:chemistry* / Q000627:therapeutic use
C503075:Clearfil Protect Bond; C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate