Live Helicobacter pylori in the root canal of endodontic-infected deciduous teeth

Many polymerase chain reaction (PCR)-based studies have shown that Helicobacter pylori DNA is prevalent in the oral cavity, but reports on the isolation of live bacteria are extremely rare. Thus, it is still unclear whether H. pylori can indeed survive in the oral environment. Here we used electron microscopy, selective growth techniques, urease assays, 16S rRNA PCR, and western blotting to investigate the possible presence of live H. pylori in 10 root canal and corresponding plaque samples of endodontic-infected deciduous teeth in three children. Although H. pylori DNA was verifiable by PCR in several plaque and root canal samples, bacterial colonies could only be grown from two root canals, but not from plaque. These colonies were unequivocally identified as H. pylori by microscopic, genetic, and biochemical approaches. Our findings show that root canals of endodontic-infected teeth may be a reservoir for live H. pylori that could serve as a potential source for transmission.