Effect of Long-term Exposure to Endodontic Disinfecting Solutions on Young and Old Enterococcus faecalis Biofilms in Dentin Canals

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• 作者：Tianfeng Du ; DDS^&lowast ; ; ^&dagger ; ; Zhejun Wang ; DDS ; PhD^&dagger ; ; ^&Dagger ; ; Ya Shen ; DDS ; PhD^&dagger ; ; Jingzhi Ma ; DDS ; PhD^&lowast ; ; Yingguang Cao ; DDS ; PhD^&lowast ; ; Markus Haapasalo ; DDS ; PhD^&dagger ; ; ^{markush@dentistry.ubc.ca" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Biofilm ; chlorhexidine ; dentinal tubules ; Enterococcus faecalis ; sodium hypochlorite
• 刊名：Journal of Endodontics
• 出版年：2014
• 出版时间：April 2014
• 年：2014
• 卷：40
• 期：4
• 页码：509-514
• 全文大小：4396 K

文摘

The purpose of this study was to evaluate the antimicrobial activity on Enterococcus faecalis biofilms in dentin canals of short-term and long-term exposure to different endodontic disinfecting solutions by using a dentin infection model and confocal laser scanning microscopy.

Methods

Dentinal tubules in semi-cylindrical dentin blocks were filled with E. faecalis by centrifugation and incubated to form 1-day-old and 3-week-old biofilms. The young and mature biofilms in dentin were subjected to sterile water, 2% chlorhexidine, 2% sodium hypochlorite (NaOCl), and 6% NaOCl for 3, 10, and 30 minutes. After treatments, the proportion of bacteria killed by the disinfectants was analyzed by confocal laser scanning microscopy by using LIVE/DEAD bacterial viability stain.

Results

The proportion of killed bacteria was lower after 3 minutes than after 10 and 30 minutes of exposure to the disinfecting agents (P < .05). The killing of bacteria in the E. faecalis biofilms was fastest during the first 3 minutes and slowed down greatly after 10 minutes. Six percent NaOCl was the most effective antibacterial solution against both the 1-day-old and 3-week-old biofilms (P < .05). No significant difference in bacterial killing was detected between 2% chlorhexidine and 2% NaOCl (P > .05). Significantly more cells were killed in young biofilms than in old biofilms in all groups (P < .05).

Conclusions

The killing of bacteria in infected dentin by disinfecting solutions is time-dependent. However, little additional killing is obtained after the first 10 minutes of exposure.