Effect of irrigation solutions on dentin bonding agents and restorative shear bond strength.
BACKGROUND
The presence of irrigation solution prior to the application of dentin bonding agents may be one source of contamination and may adversely affect bond strength.


OBJECTIVE
The purpose of this in vitro investigation was to evaluate the effect of irrigation solutions of different purity levels on the shear bond strength of a hybrid composite to dentin.


METHODS
Forty extracted, intact human molars were hand-scaled. All soft tissue was removed, and the teeth were stored in room-temperature tap water for 1 week. Subsequently, each tooth was embedded in autopolymerizing acrylic resin with the coronal portion exposed. After complete polymerization of the resin, the dentin surfaces were exposed, and the crown was cut longitudinally on all 4 sides to produce flat dentin surfaces for bonding. The prepared specimens were assigned to 4 groups of irrigation solutions: tap water (control), sterile water, 0.9% NaCl irrigation solution, and filtered water. Within each irrigation group were 4 dentin bonding agent subgroups: Prime & Bond NT, One-Step, Single Bond Adhesive, and OptiBond Solo. The dentin surfaces (n = 10 per irrigation/bonding agent pair) were etched with 37% phosphoric acid, rinsed with the assigned irrigation solution for 15 seconds, and then dried. Plastic cylinders (3 mm long x 3 mm inner diameter) were filled with a hybrid composite (Herculite XRV) and bonded to the dentin. Specimens were loaded in a universal testing machine, and shear force was applied to the base of the composite cylinders, parallel to the dentin surfaces, at a crosshead speed of 0.05 in/min until fracture. Failure loads were recorded. Bond strength data were compared with analysis of variance (P<.05). Post-hoc comparisons of means were performed with t tests and P values adjusted for multiple comparisons (Bonferroni method).


RESULTS
Tap water irrigation (control) produced no significant difference in bond strengths for all dentin bonding agents tested. When other irrigation solutions were used, One-Step consistently produced significantly lower bond strengths than other dentin bonding agents (P<.05). No preferential choice of irrigation solution could be made for Prime & Bond or Single Bond Adhesive. However, when One-Step or Solo was used, irrigation with normal saline significantly reduced bond strengths (P<.05).


CONCLUSIONS
Within the limitations of this study, the bond strength to dentin of a hybrid composite irrigated with different solutions was dependent on the dentin bonding agent used.
Sung
Eric C
EC
Division of Advanced Prosthodontics, Biomaterials, and Hospital Dentistry, School of Dentistry, University of California at Los Angeles, Los Angeles, 90095-1668, USA. ericsung@ucla.edu
Tai
Eddie T
ET
Chen
Toni
T
Caputo
Angelo A
AA
D000134:Acid Etching, Dental; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry*; D013223:Statistics as Topic; D013314:Stress, Mechanical; D007507:Therapeutic Irrigation; D014867:Water / Q000737:chemistry*
C103506:Bis-GMA, BPDM, HEMA dental-bonding resin; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; C428805:OptiBond SOLO; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; C115612:single bond; D014867:Water; C065770:Herculite XR; D012965:Sodium Chloride; D017438:Bisphenol A-Glycidyl Methacrylate