Sodium hypochlorite effects on dentin bond strength and acid-base resistant zone formation by adhesive systems

Abstract

Aim: To evaluate the effects of 10% NaOCl gel application on the dentin bond strengths and morphology of resin-dentin interfaces formed by three adhesives. Methods: Two etch-and-rinse adhesives (One-Step Plus, Bisco Inc. and Clearfil Photo Bond, Kuraray Noritake Dental) and one self-etch adhesive (Clearfil SE Bond, Kuraray Noritake Dental) were applied on dentin according to the manufacturers' instructions or after the treatment with 10% NaOCl (ED-Gel, Kuraray Noritake Dental) for 60 s. For interfacial analysis, specimens were subjected to acid-base challenge and observed by SEM to identify the formation of the acid-base resistant zone (ABRZ). For microtensile bond strength, the same groups were investigated and the restored teeth were thermocycled (5,000 cycles) or not before testing. Bond strength data were subjected to two-way ANOVA and Tukey's test (p<0.05). Results: NaOCl application affected the bond strengths for One-Step Plus and Clearfil Photo Bond. Thermocycling reduced the bond strengths for Clearfil Photo Bond and Clearfil SE Bond when used after NaOCl application and One-Step Plus when used as recommended by manufacturer. ABRZ was observed adjacent to the hybrid layer for self-etch primer. The etch-and-rinse systems showed external lesions after acid-base challenge and no ABRZ formation when applied according to manufacturer's instructions. Conclusions:10% NaOCl changed the morphology of the bonding interfaces and its use with etch-&-rinse adhesives reduced the dentin bond strength. Formation of ABRZ was material-dependent and the interface morphologies were different among the tested materials.

Assessment of Sodium Thiosulfate Neutralizing Effect on Micro-hardness of Dentin Treated With Sodium Hypochlorite

“…Structural changes caused by NaOCl as a root canal irrigant could have an adverse effect on resin-dentin bond strength for tooth reconstruction. Previous studies have reported an adverse effect of this irrigant on bond strength (14)(15)(16)(17)(18)(19)(20). Studies have shown that the adverse effect of NaOCl is due to an oxygen-rich layer forming along the dentin surface followed by the breakdown of NaOCl into chlorine and oxygen.…”

Sodium Hypochlorite Irrigation and Its Effect on Bond Strength to Dentin

“…Furthermore, the removal of exposed collagen does not only reduce the bonding technique sensitivity but also produce a more porous surface (i.e., an increase in size of dentinal tubules with the presence of an extensive labyrinth of lateral tubules that open on intertubular and/or peritubular dentin) [ 37 ] and larger resin tags [ 22 ] that would produce interfaces with high bond strength. The use of NaOCl also produced an acid-base resistant zone under the hybrid layer; this zone could help in resisting secondary caries around restorations [ 38 ].…”

Assessment of sodium thiosulfate neutralizing effect on micro-hardness of dentin treated with sodium hypochlorite

“…In contrast, Hu et al reported that time of exposures with is more important than the concentrations [13]. Structural changes caused by NaOCl as a root canal irrigant could compromise resin-dentin bond strength for tooth reconstruction [14][15][16][17][18][19][20]. Studies have shown that this effect of NaOCl is due to an oxygen-rich layer forming along the dentin surface followed by the breakdown of NaOCl into chlorine and oxygen.…”