BDJ Open 2015; DOI:10.1038/bdjopen.2015.3

Dental plaque is a complex biofilm or mass of bacteria. Biofilms are abundant in humans and are involved in a variety of infections in the body, such as pneumonia, urinary tract infections and implant-associated infections. In the mouth, the plaque biofilm is a major aetiological factor in several disease processes, including dental caries. In particular, subgingival dental plaque is a major initiating factor in periodontal diseases and is much more challenging to study due to its location beneath the gumline.

Finding out more about what biofilms are made of and how they are structured is key to developing new ways to treat biofilm-related diseases in patients. With this knowledge new methods for disrupting or inhibiting biofilm formation could be found which would be of huge benefit in many different clinical settings.

In this BDJ Open article, Richard Holliday and colleagues discuss how microscopy can be used to do just this. The team from the dental school at Newcastle University worked with a physicist (Durham University) to obtain high-resolution images of undisturbed subgingival plaque using field emission-scanning electron microscopy (FE-SEM). Previous microscopy techniques which were used to look at the structure of plaque biofilms had limited magnification and/or resolution. However, FE-SEM allowed the team to successfully examine the ultrastructure of plaque from extracted teeth in which the lateral root surface was not touched to preserve the subgingival biofilm.

The FE-SEM pictures showed many different bacterial cell shapes as expected, and allowed extracellular material in the form of strands and vesicles to be detected with a high resolution. The images also showed open-ended tubule structures in the biofilm which, to the best of the authors' knowledge had not previously been reported. The team successfully proved FE-SEM to be a useful tool for obtaining high-resolution images of undisturbed subgingival plaque.