Evaluation of the Susceptibility of Multispecies Biofilms in Dentinal Tubules to Disinfecting Solutions.
BACKGROUND
The present study evaluated the effect of the source of biofilm bacteria on their susceptibility in dentinal tubules to disinfecting solutions using an infected dentin model.


METHODS
Infected dentin blocks were prepared. Enterococcus faecalis strains VP3-181 and Gel 31 were introduced into dentinal tubules by centrifugation to form monospecies biofilms, whereas 3 specimens of pooled plaque bacteria collected from different donors were used to grow multispecies biofilms in dentin. After 1 and 3 weeks of incubation, the samples were subjected to sterile water, 2% chlorhexidine (CHX), and 2% sodium hypochlorite (NaOCl). After the 3-minute exposure, the proportions of killed bacteria in dentin canals were assessed by viability staining and confocal laser scanning microscopy.


RESULTS
The proportion of killed bacteria in mature (3 weeks) mono- and multispecies biofilms was lower than in young biofilms (1 week) after treatment (P < .05). E. faecalis Gel 31 biofilms and multispecies biofilms were more resistant than VP3-181 biofilms. No differences in the susceptibilities to the disinfecting agents of the 3 multispecies biofilms were detected; 2% NaOCl was more effective against multispecies biofilms in dentin than 2% CHX (P < .05), whereas no significant difference was detected between 2% CHX and 2% NaOCl against the E. faecalis strains.


CONCLUSIONS
Mature mono- and multispecies biofilms in dentinal tubules are more resistant to disinfectants than corresponding young biofilms. The susceptibility of the monospecies E. faecalis dentin biofilm showed strain-related differences, whereas the multispecies biofilms from different donors showed similar susceptibility.
Department of Stomatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Faculty of Dentistry, Division of Endodontics, Department of Oral Biological and Medical Sciences, University of British Columbia, British Columbia, Canada.
Yan
Y
Yang
Faculty of Dentistry, Division of Endodontics, Department of Oral Biological and Medical Sciences, University of British Columbia, British Columbia, Canada.
Ya
Y
Shen
Faculty of Dentistry, Division of Endodontics, Department of Oral Biological and Medical Sciences, University of British Columbia, British Columbia, Canada.
Zhejun
Z
Wang
Department of Conservative Dentistry and Endodontics, Guanghua School of Stomatology, Sun Yat-Sen University, Guangzhou, China.
Xiangya
X
Huang
Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan.
Hazuki
H
Maezono
Department of Stomatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Jingzhi
J
Ma
Department of Stomatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Yingguang
Y
Cao
Faculty of Dentistry, Division of Endodontics, Department of Oral Biological and Medical Sciences, University of British Columbia, British Columbia, Canada. Electronic address: markush@dentistry.ubc.ca.
Markus
M
Haapasalo
D000328:Adult; D000891:Anti-Infective Agents, Local / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects*; D002710:Chlorhexidine / Q000494:pharmacology; D003773:Dental Plaque / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology*; D004203:Disinfection / Q000379:methods*; D013293:Enterococcus faecalis / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D050296:Microbial Viability / Q000187:drug effects; D018613:Microscopy, Confocal; D008875:Middle Aged; D012388:Root Canal Irrigants / Q000494:pharmacology; D012973:Sodium Hypochlorite / Q000494:pharmacology
D000891:Anti-Infective Agents, Local; D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite; D002710:Chlorhexidine
Biofilm; dentinal tubules; disinfection; maturation; monospecies; multispecies