ABSTRACT
Objective@# To observe the effect of dopamine pretreatment of the root canal on improving the bonding performance of AH-plus sealer.@*Methods @# A total of 32 freshly isolated permanent teeth with a single canal were collected, with no caries, no fracture of roots, and a root canal curvature<10°. All sample root canals were prepared to F2 with ProTaper rotating nickel-titanium instruments and then treated with 1 mg/mL, 2 mg/mL, or 3 mg/mL dopamine solution for 24 hours and divided into 4 groups (n = 8): 0 mg/mL dopamine group (blank control group), 1 mg/mL dopamine group, 2 mg/mL dopamine group, and 3 mg/mL dopamine group. Scanning electron microscopy was used to observe the combination of dopamine and root canal dentin wall; laser confocal scanning microscopy was used to observe the penetration of AH-plus sealer; and root canal filling was performed with AH-plus sealer and gutta-percha tip using the cold gutta-percha lateral pressure technique. The root canal samples were cut horizontally at the middle and the apical third sections of the root with a slice thickness of 1-2 mm. The push-out test was carried out under an Instron universal testing machine to compare the push-out bonding strength between each group. @*Results @#Scanning electron microscopy showed that most of the dentinal tubules were open in the control group after 0 mg/mL dopamine solution treatment for 24 hours. In the 1 mg/mL group, a small number of dopamine particles on the surface of the dentin tubules in the inner wall of the root canal were loose and unevenly distributed. In the 2 mg/mL group, most of the dentinal tubules were covered by dopamine particles, and the dopamine layer was uniform and dense. In the 3 mg/mL group, a large number of dopamine particles were deposited at the mouth of the dentinal tubules, but the distribution was uneven. Dopamine and AH-plus sealer can be seen to simultaneously infiltrate into dentinal tubules under a confocal laser scanning microscope. The interaction of the two factors, the anatomical location and dopamine concentration, had no significant effects on the bonding strength of AH-plus sealer (P>0.05). Root canals treated with 2 mg/mL dopamine had the highest bonding strength in all groups (P<0.05). Analysis of the push-out test of bonding strength with AH-plus sealer at different anatomical locations showed significant differences (P<0.05). The push-out bonding strength of the AH-plus sealer in the middle third section of the root was higher than that in the apical third section of the root.@*Conclusion@# Different dopamine concentrations could affect the bonding strength of AH-plus sealer in root canals. When treated with 2 mg/mL dopamine for 24 hours, the bonding effect of AH-plus sealer in root canals was improved.