Abstract
BACKGROUND/PURPOSE: Root canal irrigants are difficult to diffuse deep into the dentinal tubules for root canal disinfection. The purpose of this study was to assess the ability of different diffusing enhancers to deliver chlorhexidine (CHX) into dentinal tubules. MATERIALS AND METHODS: The diffusing property of five diffusing enhancers (acetone, DMSO, Triton X-100, JFC-E and azone) into dentinal tubules was firstly assessed using the Rhodamine B. The ability of the diffusing enhancers to deliver CHX into dentinal tubules was then evaluated both qualitatively and quantitatively. A deep dentinal tubule Enterococcus faecalis infection model was further established to test the bactericidal effect of CHX delivered by different diffusing enhancers. Finally, the in vitro cytotoxicity of these diffusing enhancers was tested using the CCK-8 method. RESULTS: Azone, Triton X-100 and JFC-E exhibited the largest maximum diffusing depths at all root canal parts (P < 0.05). Azone group also showed the highest percentage of diffusing depths for all root canal parts, followed by Triton X-100 (P < 0.05). The percentage of dead bacteria in dentinal tubules close to cementum layer was significantly higher in the CHX + azone group than in the other groups (P < 0.05), followed by CHX + Triton X-100 and CHX + JFC-E groups. The concentration of CHX diffusing onto the exterior surface of root was significantly higher in CHX + azone group than in the other groups (P < 0.05). All the diffusing enhancers showed relatively low cytotoxicity. CONCLUSION: Azone showed the highest diffusing ability with low cytotoxicity and might be employed as a carrier agent for either intracanal irrigants or medications to achieve more thorough root canal disinfection.