Degradation of resin-dentin bonds using NaOCl storage.
OBJECTIVE
Several recent studies have reported collagen hydrolysis within bonds over the long-term. This may be one reason for the degradation of the bonds. This study therefore aimed to determine the effects of NaOCl on adhesive system bonds (total-etch bonding system vs. self-etching primer system) to dentin in order to accelerate the durability testing.


METHODS
Resin-dentin bonded specimens were produced using Liner Bond 2V (Kuraray), a self-etching primer system, and OptiBond SOLO (Kerr), a total-etch bonding system, according to the manufacturers' instructions. The bonded specimens were serially sectioned in both x and y directions across the adhesive interface to obtain beams (adhesive area: 0.9 mm(2)). The specimens were immersed in 10% NaOCl solution for 1-5h after being stored in water at 37 degrees C for 24h. Control specimens were tested without exposure to NaOCl. After storage, micro-tensile bond tests were performed. Results were analyzed by two-way ANOVA and Fisher's PLSD tests (p<0.05). All fractured surfaces were observed by SEM, and examined using an image analyzer.


RESULTS
The bond strengths decreased with increasing storage time in NaOCl. Fractography showed that NaOCl had a greater effect on the bond structure of OptiBond SOLO than on that of Liner Bond 2V, although both adhesives were susceptible.


CONCLUSIONS
Deterioration of the bonds was responsible for the effect of NaOCl on the hybrid layer. This deterioration may occur in humans in cases of deproteinization within the bonds.
Department of Operative Dentistry, Bauru School of Dentistry, University of, São Paulo, SP, Brazil.
M
M
Yamauti
M
M
Hashimoto
H
H
Sano
H
H
Ohno
R M
RM
Carvalho
M
M
Kaga
J
J
Tagami
H
H
Oguchi
M
M
Kubota
D000134:Acid Etching, Dental; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D016009:Chi-Square Distribution; D003094:Collagen / Q000187:drug effects; D001840:Dental Bonding; D003804:Dentin / Q000187:drug effects; D003806:Dentin Permeability / Q000187:drug effects*; D017220:Dentin-Bonding Agents; D004356:Drug Storage; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry; D012973:Sodium Hypochlorite / Q000737:chemistry / Q000494:pharmacology*; D013718:Tensile Strength
C112274:Clearfil Liner Bond 2; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C428805:OptiBond SOLO; D019279:Resin Cements; D017438:Bisphenol A-Glycidyl Methacrylate; D003094:Collagen; D012973:Sodium Hypochlorite