The big fat post on the oral microbiome
Periodontal (gum) issues are not only preventable but healthy gums can prevent other chronic illnesses. We are on a mission to get this information to as many people as possible.
The microbiome is an overused buzzword of our generation. It all began with the gut microbiome and Giulia Enders's wonderfully informative book, GUT. A book I read many times over. A book that led to a deeper understanding of bacteria and eventually launched 1001' good for gut microbiome' statements. Today you cannot turn left in a supermarket without a foodstuff claiming to be great for the gut bacteria. The same trajectory has followed the oral microbiome since I first heard about it at a British Society of Periodontology meeting in 2015. Now every oral product is claiming oral microbiome-enhancing benefits.
When I qualified over ten years ago, there was no teaching on the 'microbiome'. We were taught a highly reductive way of looking at the bacteria in the mouth as a series of families. Those causing tooth decay ( leading to fillings) and others causing gum disease. Some we knew were just there, but it was believed that if they increased in numbers, they too could cause oral issues. Now we know that it is much more complex than all this.
The mouth is a place for first encounters. It's the mother's kiss to the newborn, nutrients through breast milk and later food; it's the entryway to whatever we grab with our hands in early childhood and later in life medications or even any elective noxious substances we wish to try like cigarettes, alcohol or drugs. It all begins through our mouths. Thus through these processes, we are first introduced to our microbiome here. Our mouth containing teeth, gums and surrounding surfaces ( tongue, cheek, palate, throat) is home to the second most diverse microbial communities in the body, the most diverse being in the gut.
The mouth provides an ideal environment of moisture through saliva and various oxygen levels through exposed (surface of the tongue, teeth) and hidden surfaces (inner margins of the gums or folds of the throat) to encourage a mix of different types of bacterial species.
What is the oral microbiome?
The oral microbiome is a complex community of bacteria living in the mouth. They reside in all different areas, and within each area, they form tribes. Just like humans, bacteria also have a preference for community and social networking.
Within these communities, there are types which can cause harm, those which help manage the numbers of harmful bacteria and then there are those which we have identified but cannot figure out ( just yet) their role. Together they grow, replicate and nourish each other. They also communicate using chemicals to each other or their host's immune system.
In periodontics ( the study of gum health), we group the bacteria communities into different colour-coded community complexes. We have now established that there is great diversity amongst the bacteria present in the biofilm. However, some critical harmful bacteria are known. The most widely studied include Tanneralla forsythia, Treponema denticola, and Porphyromonas gingivalis. Others include Eubacterium, Aggregatibacter actinomycetemcomitans (Aa for short because even dentists can't pronounce this tongue twister), Fusobacterium nucleatum, Clostridia and Prevotella species. Microbiome testing routinely detects these species of bacteria within the saliva samples of those with periodontal issues.
Where does the oral microbiome come from?
Bacteria, viruses, fungi, protozoa and possibly other parasites are some microbial organisms inhabiting our mouths, although bacteria are the most widely studied of the lot. It is thought that we acquire our personalised microbiome through genetics from prenatal life, through local (mode of birth, breast milk, transmission from people around us in early life) and environmental factors in life that then interact with our unique immune system. Throughout life, the diversity changes based on life events (eruption of baby teeth, loss of these teeth to be replaced with adult ones), exposure to lifestyle factors such as diet (acidic versus alkaline foods), oral hygiene practices and techniques, smoking, stress etc.
So what happens when the mouth is healthy?
The oral microbiome of a healthy individual is diverse and includes all types of species, including those that have the potential to cause harm but in small insignificant numbers. This microbiome composition changes at various stages of life, from birth to senility. However, the initial bacteria we are introduced to at the beginning as neonates and newborns tend to become some of the more dominant ones throughout our life. This is why maternal (and, to some extent, parental) oral health is so important.
The oral microbiome is organised into something referred to as a biofilm (also known as dental plaque). Dental plaque is not to be confused with the hard stony substance attached to the teeth' surface, known as calculus. However, calculus can increase biofilm retention towards the tooth surface (confusing, I know!).
A biofilm is many different microbes living in harmony with their host human in a process we know as commensal. They rely on their host for nutrition and home but grow, communicate and protect one another from external harm while providing some key benefits to their hosts when they are in small quantities. Benefits we know about include protection against the growth of harmful disease-causing bacteria and providing byproducts that aid in things like blood pressure, obesity regulation and taste alternations. Another benefit being studied in animals but not yet translated to humans is the microbiome's role in anticancer activity through a bacterial byproduct called nisi
What about disease?
Biofilms do not like change or neglect (much like the humans they inhabit). Suppose the biofilm is left unattended (i.e. through poor oral hygiene), and its profile changes. This can result in two significant events facilitating the initiation and development of gum disease. First, the increase in quantity will create an opportunity to grow intermediate species of bacteria. Intermediate bacteria species' orchestrate a change toward attracting opportunistic disease-causing bacteria. Second, the biofilm hardens to include minerals from the saliva, creating calculus. Calculus attaches to hard tooth surfaces and cannot be removed by home oral hygiene practices. Calculus is rough and an ideal breeding space for even more harmful bacteria. Once calculus develops, it needs to be removed professionally, usually by dental hygiene professionals (more on these dental heroes in a few weeks).
The process described above is a finely tuned balanced act maintained through various immune system interactions but oral hygiene plays a key role. Once the balance is disturbed, dysbiosis ensues (a change in the quality and quantity of the microbiome). Dysbiosis results in immediate immune response activation through inflammation (gingivitis in the beginning). If such an immune activation is left without intervention, the inflammation becomes chronic, leading to the slow self-destruction of the tooth's ligaments and bone. We call this periodontitis ( various stages explained a few weeks ago here!).
What is the oral microbiome's connection with the rest of the body?
Bacteria in the oral cavity pop up in other parts of the body, particularly in other organs during chronic illnesses. It is believed that bacteria link the mouth to the rest of the body.
There are three ways this happens; direct spread like classic infections, the release of bacterial toxins through circulation in the blood, and the immune system activated inflammation which goes from being local to systemic.
There is now a considerable body of evidence to support the presence of P. gingivalis wherever there is inflammation. So far, this has been the most significant indicator that there is way more than we know about oral bacteria and the rest of the body. Exact mechanism pathways are under study, and we hope to share them in this newsletter as it all reveals itself.
Meanwhile, Prevotella species have been detected in conditions such as polycystic ovary syndrome (PCOS). It has also been shown that oral microbiome species may also influence their host's taste preferences.
The link between oral and systemic health will play a significant role in the future. There are already scientists from other fields working with dental professionals to improve understanding. Courses like this one are being offered to students from an early on in their careers.
With a collaborative effort from different fields, the future seems promising for oral health and overall wellbeing (if only we could get the politicians and policymakers on board).
All images in today’s post by Orfayo - one of our fave artists ( please check them out!)
If you made it this far (a big thank you and we appreciate your valuable time and attention), we hope we were able to simplify a complex topic of the oral microbiome. If you have any questions or feedback, please email or DM us on Instagram @thegumguide. Please note that we cannot diagnose and give personalised health advice ( kindly see your dental professional for that).
Lastly, if you found this post useful (you may have even found it fun!), please share it with friends & family. See you next week ;)