Bacterial flora and extraradicular biofilm associated with the apical segment of teeth with post-treatment apical periodontitis.
BACKGROUND
Microorganisms are able to survive and cause persistent infection in the extraradicular area. The aims of this study were to investigate the primary bacterial flora and the localization of extraradicular biofilm in persistent apical periodontitis lesions.


METHODS
Apical root samples from root-end surgery were collected from 23 root-filled teeth with apical periodontitis. Five samples were examined for the presence of biofilm by scanning electron microscopy. Another 5 samples were examined for the presence of biofilm by Brown and Brenn-modified Gram staining. The DNA from 13 samples was processed for amplification via polymerase chain reaction and separated with denaturing gradient gel electrophoresis. Selected bands were excised from the gel and sequenced for identification.


RESULTS
The extraradicular biofilm present on the external root surface of treated teeth consisted of abundant, amorphous extracellular material and multiple bacterial species. The following species were detected in the microbial community from the apical samples: Actinomyces sp. oral, Propionibacterium, Prevotella sp. oral, Streptococcus, Porphyromonas endodontalis, and Burkholderia. The prevalence of Actinomyces sp. oral and Propionibacterium were highest (84.6% and 61.5%, respectively).


CONCLUSIONS
Extraradicular biofilm was present on the external root surface of treated teeth with persistent periapical lesions. Actinomyces sp. oral and Propionibacterium are likely important contributors to extraradicular biofilm formation and persistent periapical infection.
Department of Endodontics and Operative Dentistry, Shanghai Key Laboratory of Stomatology, Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Juan
J
Wang
Yuntao
Y
Jiang
Wu
W
Chen
Cailian
C
Zhu
Jingping
J
Liang
D000190:Actinomyces / Q000302:isolation & purification; D000328:Adult; D001047:Apicoectomy; D018441:Biofilms / Q000254:growth & development*; D058645:Denaturing Gradient Gel Electrophoresis; D003739:Dental Cementum / Q000382:microbiology*; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D007180:Incisor; D008297:Male; D008437:Maxilla; D058889:Molecular Typing; D010485:Periapical Periodontitis / Q000209:etiology / Q000382:microbiology*; D011424:Propionibacterium / Q000302:isolation & purification; D019233:Retreatment; D012390:Root Canal Therapy / Q000009:adverse effects*; D017422:Sequence Analysis, DNA; D019227:Tooth Apex / Q000382:microbiology / Q000601:surgery