Effect of lactic acid irrigant on shear bond strength of Epiphany adhesive sealer to human dentin surface

Abstract

To examine the effects of varied dilutions of lactic acid as a root canal irrigant and compare the shear bond strength of Epiphany adhesive sealer to human dentin surface with other solutions deemed to be suitable root canal irrigants. The occlusal surfaces of 60 extracted molar teeth were ground wet and treated with one of the following irrigants: 1) no irrigant (control); 1) 5% hydrogen peroxide; 3) 5% sodium hypochlorite; 4) 15% ethylenediaminetetraacetic acid (EDTA); 5) 10% lactic acid; or 6) 20% lactic acid. An additional specimen for each group was critical-point dried and freeze-fractured to evaluate the dentin surfaces after treatment by scanning electron microscopy. Specimens were treated with Epiphany primer, hollow steel tubes were placed on the dentin surfaces, and resin sealer (Epiphany) was applied to dentin inside the tubes. Specimens were stored in 100% humidity, then loaded to failure in a universal testing machine in the shear mode with a cross speed of 0.05 mm/min. Dentin surface treatment resulted in significant differences for surface topography and shear bond strength of Epiphany sealer (P < .001). Lactic acid and EDTA significantly improved epiphany- dentin bond strengths when compared with other irrigants (P < .001). The highest mean (SD) bond strength was 1.95 (0.47) MPa for dentin surfaces treated with 20% lactic acid. The lowest mean bond strength [0.41 (0.29) MPa] was associated with untreated dentin surfaces. Scanning electron micrographs showed that the surface of the control specimens had a smear layer that contained smear plug material. Similarly, hydrogen peroxide and sodium hypochlorite produced surfaces with a smear layer. Lactic acid solutions and EDTA, however, removed the dentinal smear layer but left remnants of smear plugs in the dentinal tubules. Lactic acid irrigant performed similarly to 15% EDTA and demonstrated higher bond strength of Epiphany sealer to dentin surface.