As dental professionals, we are very attuned to understanding how dental plaque and biofilms contribute to dental diseases. However one area that is still being understood better is the role of the oral microbiome and how it supports the natural functions of the oral cavity. This article I have written for Colgate Palmolive breaks down what the oral microbiome is and why it plays a pivotal role in helping our patients optimise their oral health.
What is the Oral Microbiome?
The oral cavity has the second largest and second most diverse microbiota after the gut, and contains a collective of microorganisms that colonise the hard and soft tissues of the mouth. This forms an important ecosystem of bacteria, fungi, virus and protozoa that can promote health if in good balance, or lead to disease processes when unbalanced. The oral microbiome was first identified by Antony Van Leeuwenhoek after observing his own dental plaque under a microscope in 1674.1
The diversity of the human microbiome, especially the oral microbiome, can be attributed to two components - the common microbiome and the variable microbiome. The common microbiome is found amongst all humans, however the variable microbiome is more unique to individuals and is dependent on lifestyle and physiological choices. These microorganisms colonise both hard and soft tissues of the oral mucosa. Whilst teeth are the common known hard tissue site of colonisation, the tongue, cheeks, gingival sulcus, tonsils, hard palate and soft palate provide a suitable environment for microbes to flourish. The plethora of bacteria that coat these surfaces are better known as bacterial biofilm. When the oral cavity provides a stable environment of an average core body temperature of 37℃ and salivary pH of 6.5 - 7, this allows bacteria to stay hydrated and also have nutrients transported via saliva.1
Since the oral microbiome usually exists in the form of bacterial biofilm, it is important to distinguish the general function of this collective of microorganisms. All contributing to maintaining homeostasis of the oral cavity, the oral microbiota play a critical role in physiological, metabolic and immunological functions not limited to digestion of food and nutrition, balancing pro-inflammatory and anti-inflammatory processes of the immune system and regulating fat storage.2
Helpful vs Harmful Biofilms
In a healthy state, biofilms form on the teeth and soft tissue surfaces, mainly consisting of benign “helpful” bacteria. These beneficial biofilms help the oral cavity shield against non-oral microbes and restrict the growth of pathogenic microorganisms that contribute to oral disease processes like dental caries and periodontal disease. When a neutral pH is maintained, symbiotic, beneficial biofilms create an important homeostatic balance for normal bodily function.2
When a healthy microbiome is altered by a person’s physiology of lifestyle behaviours, this enduring unbalanced state, sometimes referred to as dysbiosis, leads to proliferation of “harmful” biofilms at the gingival margin. This contributes to gingival inflammation and changes in the bacterial populations, favouring the disease-causing bacterial strains that undermine and inhibit the body’s immune systems. The resultant destruction of the tissues and bone surrounding teeth becomes the basis of periodontal disease pathogenesis.2
Similarly, the proliferation of cariogenic bacteria on the biofilm on teeth surfaces contributes to the secretion of demineralising acids when in contact with sugars from the diet. This, coupled with the decrease in bacteria that secrete acid-neutralising alkalis, means the protective effect on dental caries is reduced and favours disease progression.2
How to support the oral microbiome?
Since the harmful biofilms accumulate over time by sticking to the teeth and soft tissues of the oral cavity, frequent cleansing and removal of these biofilms can allow healthier bacteria to proliferate. This is the foundation behind why good oral hygiene habits, including brushing and flossing twice daily, help support the oral microbiome. Having a well balanced and nutritious diet is equally important to supporting healthy biofilms to flourish since diets high in sugars are well known factors leading to increased dental caries risk. Finally, another great way to support homeostasis of the oral microbiome is the use of probiotics. Probiotics are the use of live strains of bacteria and yeasts that are traditionally associated with the gut microbiome to target the harmful bacteria and promote proliferation of good bacteria to support gut health. Research is now showing there is an oral benefit to probiotics: some dental probiotics now can target problematic bacteria by producing antimicrobial compounds that reduce the capacity of dental plaque to grow within the mouth.3 Reducing plaque accumulation also leads to decreased gum inflammation, and some probiotic strains also modulate the immune system to support the anti-inflammatory processes. This can bring the oral cavity from an unbalanced, dysbiotic state to a healthy state once more.3 Aside from probiotic supplements, there are some foods one can include in the diet which also contain probiotic properties. These include dairy sources such as yoghurt, kefir, cultured cottage cheese and buttermilk. Non-dairy sources include fermented vegetables such as sauerkraut and kimchi. There are also some foods that act as prebiotics, which are plant fibres that act like fertiliser to probiotics and enhance their effectiveness. Prebiotic foods include raw Jerusalem artichokes, hickory root, oats, as well as unrefined barley and wheat.4
One area that is still being researched and developed is a future diagnostic test, which through a salivary plaque sample of a patient, can enable us as dental professionals to be able to map, measure and identify the strains prevalent in a patient’s oral microbiome. Being able to measure which strains are present before and after modification of the oral microbiome will be important to not only form evidence-based treatments for the oral microbiome but also to better treat our patients on an individual basis.5
References
Deo PN, Deshmukh R. Oral microbiome: Unveiling the fundamentals. J Oral Maxillofac Pathol. 2019;23(1):122-128. doi:10.4103/jomfp.JOMFP_304_18
Colgate-Palmolive Company. Whole Mouth Health: The Next Generation of Everyday Prevention for Oral Health. Colgate-Palmolive Company. 2019. Accessed October 26, 2024. https://www.colgateprofessional.com/content/dam/cp-sites/oral-care/professional/global/general/pdf/colgate-whole-mouth-health-whitepaper-final-min.pdf
Makeham B. What is the oral microbiome and why does it matter? Activated Probiotics. August 7, 2023. Accessed October 26, 2024. https://activatedprobiotics.com.au/what-is-the-oral-microbiome/
Colgate-Palmolive Company. Are Probiotics Good For Oral Health? Colgate-Palmolive Company. February 13, 2023. Accessed October 26, 2024. https://www.colgate.com/en-us/oral-health/plaque-and-tartar/probiotics-for-oral-health#
