Effects of sodium ascorbate on microtensile bond strength of total-etching adhesive system to NaOCl treated dentine.
OBJECTIVE
The purpose of this study was to determine the microtensile bond strengths of total etching adhesive systems to pulpal chamber wall dentine after treated with various irrigants.


METHODS
Thirty extracted human third molars were cut horizontally to expose the pulp horn. The roof of the pulp chamber and pulp tissues were removed. The teeth were then divided into five groups of five specimens each to treat with various irrigants. Specimens in each group were treated as follows: group 1, with water for 10 min; group 2, with sodium hypochlorite for 10 min; group 3, with sodium hypochlorite for 10 min and water for 10 min; group 4, with sodium hypochlorite for 10 min and sodium ascorbate for 10 min; group 5, with sodium hypochlorite for 10 min, sodium ascorbate for 10 min and water 10 min. Treated specimens were dried, bonded with a total-etching adhesive system (single bond) and restored with a resin composite (Z250) then kept for 24 h before determination of the microtensile bond strengths.


RESULTS
Group 2 (20.96+/-9.23 MPa) demonstrated significantly lower bond strengths than group 1 (30.06+/-10.44 MPa). No significant differences in bond strengths were found between group 3 (23.08+/-6.94) and group 2. Group 4 (40.55+/-8.99) demonstrated higher bond strengths than group 2. However, there were no significant differences between group 5 (24.55+/-9.73 MPa) and group 2.


CONCLUSIONS
Sodium hypochlorite significantly reduced the bond strengths of the adhesive when a total-etching was applied. The application of sodium ascorbate on sodium hypochlorite treated dentine significantly improved the bond strengths.
Vongphan
Nataya
N
Department of Operative Dentistry, Faculty of Dentistry, Mahidol University, 6 Yothi Street, Phayathai, Bangkok 10400, Thailand. dtnvp@mahidol.ac.th
Senawongse
Pisol
P
Somsiri
Waraporn
W
Harnirattisai
Choltacha
C
D000134:Acid Etching, Dental; D000268:Adhesiveness; D001205:Ascorbic Acid / Q000737:chemistry*; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003786:Dental Pulp Cavity / Q000648:ultrastructure; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D012388:Root Canal Irrigants / Q000737:chemistry*; D012973:Sodium Hypochlorite / Q000737:chemistry*; D013499:Surface Properties; D013718:Tensile Strength
D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D012388:Root Canal Irrigants; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D012973:Sodium Hypochlorite; D001205:Ascorbic Acid