For every human cell in our bodies, there are ten bacterial cells. The mouth alone contains an estimated 20 billion bacteria. They live together in complex structures called biofilms, and since ancient times humans have used various tools to remove the oral version – commonly referred to as dental plaque – from our tooth surfaces.
You are probably familiar with the idea of removing plaque to prevent the tooth surface from decaying – but what about the gums?
These vital tissues surround and support our teeth, holding them in the jaws. And unlike the inert surface of a tooth, gums are able to react to bacteria and send help signals to our immune system to join the battle. But while small numbers of health-promoting bacteria are important to keep our gums healthy, if plaque is allowed to build up, bad bacteria – known as pathogens – are able to establish themselves, and the gums become inflamed.
In its mildest form, this inflammation is called gingivitis, which is often accompanied by bleeding – as demonstrated by spitting a small amount of blood into the sink after brushing. Gingivitis is reversible and can be remedied by effective and vigilant cleaning, which is fortunate, as 90 per cent of people have some gingivitis. A trip to the dentist or hygienist may kick-start this healing process by having the teeth scaled to remove hard-to-reach plaque or its calcified cousin calculus (tartar).
In some people, if gingivitis is left untreated for a long period of time, it may transition into the more serious and irreversible inflammatory condition periodontitis. This can affect half the population, particularly as we get older, while a tenth of people will develop the severe form of the disease. Here, the bacteria move to the spaces between the teeth and gums, known as the gingival crevice, where there is little oxygen or carbohydrates available to them. The bacteria break down gum and blood proteins to stay alive and often excrete sulphur products that contribute to bad breath.
As with gingivitis, periodontitis is associated with increased bleeding of the gums. It is known that small amounts of bacteria in the gingival crevice can enter the blood stream and affect the health of the rest of the body. Indeed, the worse the gum disease, the larger the numbers of bacteria entering the blood stream during brushing or eating.
Several studies have been conducted to look at the association of periodontitis with other systemic diseases, including diabetes, heart disease, chronic kidney disease and obesity. For example, the periodontal research group at the University of Birmingham has found higher death rates in periodontitis sufferers, as well as stiffer arteries in kidney disease patients and poorer kidney function in those who have periodontitis compared with those who are disease-free.
Losing our teeth as we age is not inevitable, and looking after them is extremely important: they are essential for good nutrition and health as we age. Preventing plaque build-up may help to reduce the burden on the immune system, which declines as we get older. In turn, this may help ensure sustained good health and decrease the severity of some of the diseases mentioned above.
So, are we doing enough to keep plaque bacteria at bay? The recommended time for brushing is two minutes, twice a day – but very few people manage this. Furthermore, those hard-to-reach places between the teeth – the interdental spaces – are even more neglected. Regular use of interdental brushes makes a huge difference in minimising the risk of developing periodontitis. Disruption of the plaque biofilm and removal of potentially harmful bacteria are key to keeping the dentist at bay.
At Birmingham, we are exploring how we can help to change people’s understanding and habits around oral health. As part of this work, we took part in a TV programme called The Truth about Teeth, which will be broadcast on BBC One at 9pm on Thursday 11 June.
We are asking people to fill in a questionnaire based on the show or, for those living in the Midlands, take part in a focus group about the programme. For further information, visit our website or send us an email.
Dr Melissa Grant
Lecturer in Biological Sciences, School of Dentistry, University of Birmingham