Author(s): Shigenori Suzuki, Yoshiko Masuda, Hirobumi Morisaki, Yoshishige Yamada, Hirotaka Kuwata and Takashi Miyazaki
Objective: Citric acid has been reported removal of smear layer, low antibacterial property, low cytotoxicity. Although the citric acid alone has few used as a root canal irrigant, citric acid formulation with antibacterial effect such as MTAD and Tetraclean has already produced. However, these formulations tended to produce bacteria resistant to antibiotics such as tetracycline and others.
Chitosan have been reported broad spectrum of antibacterial properties, high chelating ability for various metal ions in acidic conditions, biocompatibility and biodegradability. Therefore, we focused on citric acid as a solution to dissolve chitosan. The purpose of this study was to determine whether chitosan-citrate solution shows antibacterial properties against Enterococcus faecalis and removes the smear layer when used as a root canal irrigant.
Methods: E. faecalis (4532D) was incubated in brain-heart infusion broth. Chitosan-citrate solution was then added to the bacterial inoculum for 5, 15, 30, and 60 min. Survival rates of E. faecalis were statistically analyzed using one-way repeated measures ANOVA and Tukey test. Extracted teeth were used for this experiment. The middle third of the root was cut longitudinally, and all specimens were immersed in chitosan-citrate solution until an antibacterial effect was obtained. All specimens were examined under scanning electron microscopy. The number of open dentin tubules was determined for evaluation of smear layer removal. One-way repeated measures ANOVA and Tukey test were used for analysis of open dentin tubules.
Results: The antibacterial effect of chitosan-citrate solution was achieved at 5 min. Furthermore, chitosan-citrate solution resulted in a significantly greater reduction of the survival rate than 10% citric acid after 5 min of application (p<0.01). The smear layer was also removed after immersion in chitosan-citrate solution for 5 min. Chitosan-citrate solution removed significantly more of the smear layer than 10% citric acid (P<0.05).
Conclusion: In conclusion, chitosan-citrate solution showed antibacterial activity and enabled removal of smear layer. As this ability depended on chitosan, it is considered that the action was enhanced by chitosan. Chitosancitrate solution has been indicated as a possible root canal irrigant.
