| biofi lm The oral biofi lm: What you should know By DTI As research into the complexities of the oral micro- biome—the community of microorganisms that exist in the mouth—continues to progress, so too should our own knowledge of it. Though the existence of dental plaque has been known about for decades, dental caries nevertheless remains the most common chronic disease globally. The World Health Organization estimates that 60 to 90 per cent of school-aged children worldwide suffer from caries and that 15 to 20 per cent of adults between the ages of 35 and 44 have severe periodon- tal disease. Clearly, our approach to this issue needs to change. What is a biofi lm? A biofilm is a dense accumulation of bacteria, fungi or protozoa that adhere to each other and to solid sur- faces. In our bodies, biofilms develop on teeth, tissue cells and the exterior of implants. Though they can have a positive role in many environments, the presence of certain biofilms may also lead to negative outcomes, such as infection. Once a microbial cell has attached it- self to a surface, it produces an extracel- lular polymeric matrix. This matrix essentially helps not only to bond these cells together, but also to protect the cells from external at- tacks. This community of microbes, together with their extracellular product, constitutes a biofilm. The microbial cells in biofilms in the human body are generally resistant to antibiotic treatments and natural im- mune system responses, allowing them to subsequently thrive. Because of this, biofilms are considered to be an ideal state of existence for microbes. Biofilm and infections Biofilms are estimated to be the cause of somewhere between 60 and 80 per cent of all bacterial infections in the human body. Though there are certain strategies to treat these infections that can prove successful, the diversity of the oral microbiome and its habitats means that special consideration must go into maintaining its balance. The composition of oral biofilms Our mouths play host to a variety of biofilms, both good and bad. Socransky et al. attempted to define this bac- terial distribution in a 1998 study of the oral biofilms of individuals both with and without periodontitis. In col- lecting over 13,000 dental plaque samples, they found that there were six major complexes that could be con- sistently observed together. These complexes were then colour-coded into red, orange, yellow, green, purple and blue groups. The blue, green, yellow and purple Socransky com- plexes were found to correlate to periodontal health, whereas orange and red complexes generally indicated the presence of periodontal disease. When present by itself, Porphyromonas gingivalis—one component of the red complex—can cause the loss of alveolar bone. When found alongside Tannerella forsythia and Treponema denticola, it often leads to periodontal disease, which has itself been linked to a variety of systemic diseases. Dental plaque biofilm Dental plaque biofilm is most commonly found on the surfaces of our teeth. It is most widespread when there is a lack of correct oral hygiene. This biofilm is the pri- mary causative factor for dental caries, periodontitis and peri-implantitis. Dr Phil Marsh, Professor of Oral Microbiology at the Uni- versity of Leeds in the UK. If dental plaque biofilm is not removed via mechan- ical or chemical control within 24 hours of forming, it will release virulent, acid-producing and acid-tolerating bacteria, triggering an inflammatory response—gingivi- 32 prevention 1 2018