In vitro study on cleaning effect of different rinsing agents combined with ultrasonic swaging on root canal wall and dentin microstructure

Objective To evaluate the effect of sodium hypochlorite and Ultra Clean on root canal cleaning and dentin structure. Methods A total of 129 single canal isolated teeth were collected and root canal was prepared to M # with Waveone Gold nickel titanium file. After preparation, they were divided into 3 groups by random number table according to irrigant:group A sodium hypochlorite + normal saline, group B sodium hypochlorite +EDTA, and group C sodium hypochlorite +Ultra Clean. The dye was stained with 1% methylene blue solution, and the penetration depth and range of the dye solution were observed under a type microscope. The removal of debris and stain layer in the root canal was observed by digital camera and scanning electron microscope. The change of dentin microstructure was analyzed by Fourier infrared spectrometer. Results In the upper middle part of the root canal, the penetration depth and range of group C were greater than those of groups A and B (P<0.05); the percentage of debris in group C was lower than that of groups A and B (P<0.05), and the stain layer score in groups B and C was lower than that of group A (P<0.05). In the lower root canal segment, groups B and C were superior to group A in the evaluation of permeability, debris and stain removal (P<0.05). The demineralization ability and exposure of dentin collagen fiber in group C were higher than those in group A and blank group (P<0.05). Conclusion Sodium hypochlorite combined with Ultra Clean is considered to have good cleaning effect and strong demineralization ability, but it may slightly increase the exposure of organic matter such as collagen fiber.