Part 10. Sustaining Host and Ecological Co-existence within the Habitat of the Mouth. A Whole Dental Health Journey.




One can walk down any supermarket aisle and gaze in awe at the array of colourful, cleverly packaged and marketed dental health products. I have spent more years than I care to mention promoting their use to clients, many I now suspect wouldn’t have benefited from my sage advice. Upon consideration I’ve come to the conclusion it may have been smarter to have avoided them all together, in most cases, and trod a more prosaic path. Let me expand more upon reflection. From David Attenborough to Greta Thunberg, we are being actively, perhaps reluctantly, driven into an age of greater environmental awareness, or to be more honest it appears, a lack of it. The increasing urgency in preventing irreparable damage to the ecology of our planet, reducing global warming and protecting innumerable endangered species, us prophetically amongst them, the willing antagonist and unbeknownst victim, has gathered resonance, even amongst our clients and within our workplaces.

“Use the best available evidence resulting from scientific research, or if absent, strong theoretical rationale, suggestive evidence, or the opinion of respected authorities.”  Section 20. Professional Standards Framework, New Zealand Dental Council.

There are now three principle aspects of sustainable practice in my clinical world, what I would term the glocal, the clinical and the oral. The glocal is the local and global environment, what we see in the present grass roots pressure groups and political movements championing the cause. Then we have our workplace and clinical environments, the materials and energy we consume and their carbon footprints from source. The oral model is the theoretical recognition that the ecology and habitat in which they dwell require similar ethical consideration, promotion and preservation. Should we continue to advocate a particular method of treatment that locally debrides the microbial habitat within our mouths? Should we learn to be less intense clinically, when in balance, when stable, and more collabotrative and aware of their potential dental and health benefits?

We “seek to provide to patients a holistic dental experience that is aimed at providing the best dental preventative care”. My Practice Strategic Draft Plan.

Picture the scene, of a mutually beneficial ecological balance, serving all who positively participate in its management. Imagine this within your mouth, it being seeded at birth, nurtured through the burgeoning early months and years of life where the landscape gradually grows and evolves. New hyper-mineralised structures erupt, in sequence, bringing with them hard surfaces ripe for colonization. Soft, rough and sleek structures shedding and sluffing, a mixture of gases flowing in and out, regular temperature changes, the ebb and flow of acidity, alkalinity and resident moisture, lubricating and assisting, in its function. Consider what dwells, lives and thrives within that place and its ecological potential for both dental and general health. Could there be a case for a similar, sustainable and environment movement in our mouths? Isn’t this what a dental healthcare professional should be focused upon when considering a holistic approach to care? My journey is to consider this in the context of this learning year, within the bounds of my present practice and professional standards.

Our oral microbiome (OM) is a natural structure and has a symbiotic relationship with us, the host, delivering important health benefits in sustaining a mutually shared ecological co-existence. We as humans form a super organism or “holobiont”, an assemblage of us with many other species living in and around us, forming one ecological unit. Less than half our body, approximately 43%, is human, being made up of 20,000 instructional genes, added to our microbiome of between 2 and 20 million microbial genes. We are home to 500-1000 species of bacteria at any one time, our body’s trillions of microorganisms making up about 1 to 3 percent of the body’s mass, that’s about 2 to 6 pounds per adult.

“What you see is that the most outstanding feature of life’s history is a constant domination by bacteria”. Stephen Jay Gould

Our mouth houses the second most diverse microbial community in the body, harbouring over 700 species of bacteria colonising hard and soft structures of the mouth. The OM is highly regulated, is structurally and functionally organised as a community. The oral habitat constitutes teeth, gingival sulci, a tongue, lips, cheeks, a hard and soft palate and attached gingivae, each offering the right conditions for a variety of distinct bacterial diversity to flourish. However, the modern day excessive consumption of acidic drinks and refined sugar, or cigarette smoking has deeply impacted upon this ecosystem and beyond.

The health of the oral microbiome has been studied to identify the causes of its dysbiosis, one is which the diversity and relative proportions of species or taxa within the microbiota are disturbed, leading to pathological changes. Research into preserved hunter-gatherer dental calculus has seen the shift from beneficial bacterial composition and declines in microbial diversity witnessed in Neolithic man. This has seen to further increase with the introduction of the modern industrial diet supplying greater amounts of more highly processed food and drink. The external environment with widespread and increased use of pesticides, heavy metals, antibiotics and antiseptics contribute significantly too . Consequently, the adaption of species that can develop defences against increased oxidative stress and resistance against acid production has prevailed. This negative change in the numbers and proportions of cariogenic and periodontal pathogenic bacteria has altered the competitiveness and encourages the selection of species best suited to this new environment. The dysbiosis of the OM is also associated with the detriment of general health.

In health the OM is beneficial to the;

  • Digestive tract, stimulating mucus production.
  • Resisting pathogenic colonisation.
  • Regulation of the cardiovascular system.
  • Host defence mechanism.
  • Production of anti-inflammatory properties.
  • Bodies metabolic potential and anti-oxidant activity.

An interesting example of how the OM support systemic health is in its supplementation of the hosts Nitric Oxide production. It helps reduce dietary nitrate converting it to nitrite, in turn having the potential to provide important symbiotic functions in human blood pressure physiology. Negative changes in the OM can increase blood pressure. The majority of these beneficial bacteria are found on the surface of the tongue, its cleaning appears to favour the increased metabolism and abundance of nitrate to nitrite production.

The flow of saliva is also a vital function to improving health affording benefits of;

  • Lubrication, helping in speech.
  • Dilution of sugars from food and drink intake.
  • Antimicrobial action through proteins and peptides including mucins, lactoferrin, lysozyme, lactoperoxidase, statherin, histatins, and secretory immunoglobulin A.
  • Buffering of acids from low to higher pH.
  • Providing substrate that supports the growth of beneficial bacteria.
  • Remineralisation and repair with the saturation of calcium and phosphate into saliva and teeth.

In addition Saliva;

  • Prepares food prior to digestion, enhancing chewing and swallowing, then clearance.
  • Aids digestion and food breakdown chemically with enzymes.
  • Enhances tasting.
  • Acts as a delivery system for components of innate and adaptive host defences.

Saliva is a solution composed of 99 percent water, 1 percent electrolytes and proteins from three salivary glands being controlled by the autonomic nervous system. It has a flow rate of 0.4 – 0.5 ml per minute in healthy subjects. Healthy biofilms  are associated with pH values of between 6.5 -7.5, this creates homeostatic and nutritional interdependency amongst bacteria. This in turn suppresses and restricts the growth of pathogenic bacteria. When acids are produced, the oral OM compensates by alkaline generation. Critical pH value begins at 5.5 when mineral begins to dissolve and loss occurs, above that value saliva and plaque are super saturated with tooth mineral with repair and remineralisation occurring as a result of bicarbonate buffering.

The stimulation of saliva flow is critical for oral balance in many situations from dry mouth to lower pH values. The use of non-nutritive sugar alcohol sweeteners like sorbitol, xylitol and erythritol can be consumed in a various forms, either in gum or lozenges, added to toothpastes or rinses and used in refined powder form in professional polishing devices clinically. They can also be purchased in granulated forms in health shops. Sorbitol and xylitol treatments have been seen not to affect microbial profiles of saliva and plaque in a 3 week study, with sorbitol increasing the amounts of commensal germs in comparison, effective in particular against Porhyromonas Gingivalis, a periodontal pathogen. However, In combination with erythritol xylitol has been seen to reduce development of cariogenic bacteria such a S. mutan.

Erythritol, a 4 carbon chained sugar alcohol, appears to offer more bacterial support. It is produced from glucose by a fermentation process and research demonstrates better efficacy than sorbitol or xylitol. It can afford;

  • Reduced plaque weight and counts of S. mutan in saliva and dental biofilm.
  • Effective absorption via the small intestine and is not systemically metabolised, being excreted unchanged within urine.
  • Zero increases in blood sugars or insulin.
  • Non-caloric benefits and higher gastrointestinal tolerance.
  • Possible improved endothelial function in people with Type 2 Diabetes.
  • Less maturation of oral biofilms and may contribute to healthy oral ecosystems.

Prebiotics are compounds found in food that induce growth or activity of beneficial microorganisms. Some species of commensal streptococci generate energy from arginine, an amino acid.  The metabolism of arginine can lead to ammonia production that can help increase environmental pH.  Ammonia is a compound of hydrogen and nitrogen. Many arginolytic bacteria produce hydrogen peroxide impacting on species associated with periodontal diseases. Probiotics, living microorganisms that deliver health benefits, have yet to have sufficient systematic review evidence to fully support its use dentally. There is little current evidence supporting the reduction dental caries but promising research in certain strains of Streptococcus has been found to express arginine deiminase , thus helping to inhibit the growth and block key functions of S. mutans, raising pH and producing bacteriocins that kill S. mutans. Additionally, small benefits are being seen in the management of gingivitis and periodontitis.

Am I simply a vehicle for numerous bacteria that inhabit my microbiome? Or are they hosting me? Timothy Morton

Simply eradicating all OM sub and supra gingivally, without exception, in pursuit of biological balance allows the onus on dental health promotion as being primarily focused instrumentally. This bellies the benefits of educational an ecological approaches, working in harmony with nature rather than obliterating it where it presents as healthy. Each and every oral health assessment needs to be mindful of the benefits of a balanced OM, not blinded by visual plaque levels but the degree to which it appears dysbiotic. Bleeding on probing on intra-oral examination and observing historical risk needs a blended approach with dietary and other lifestyle behaviour advice and management. This will require greater use of clinical time in communicating this environmental and sustainable dental message. Being more holistic in its nature, it can also embrace the broader general health benefits of the symbiotic relationships between host, saliva and OM.

The “Mouth is the gateway to the total body wellness, thus oral microbiome influences overall health of an individual”. Sharma et al.

I can envisage little resistance from many of my clients who have environmental values like myself. My workplace markets itself as being natural but I do anticipate discourse with colleagues as to my application of my interpretation of holistic and sustainable practice.

Resources More than half your body is not human. In Sickness and in Health-What Does the Oral Microbiome Mean to Us? An Ecological Perspective. Marsh, 2018. Can xylitol used in products like sweets, candy, chewing gum and toothpaste help prevent tooth decay in children and adults? Riley et al, 2015. Effect of erythritol on microbial ecology of in vitro gingivitis biofilms. Janus et al, 2017. Exploration of singular and synergistic effect of xylitol and erythritol on causative agents of dental caries. Koljalg et al, 2020. Erythritol Functional Roles in Oral-Systemic Health. De Cock, 2018. role of natural salivary defences in maintaining a healthy oral microbiota. Pederson & Belstrom, 2019. Oral microbiome and health. Sharma et al, 2018. Erythritol Is More Effective Than Xylitol and Sorbitol in Managing Oral Health Endpoints. De Cock et al, 2016. The Effect of Xylitol on the Composition of the Oral Flora: A Pilot Study. Soderling et al, 2011. effect of xylitol on dental caries and oral flora. Nayak et al, 2014. Xylitol and sorbitol effects on the microbiome of saliva and plaque. Rafeek et al, 2019. Saliva A review of its role in maintaining oral health and preventing dental disease. Dodds 2015. Oral microbiomes: more and more importance in oral cavity and whole body. Gao et al, 2018. Human Oral Microbial Ecology and Dental Caries and Periodontal Diseases. Liljemark & Bloomquist, 1996. The oral microbiome – an update for oral healthcare professionals. Kilian et al, 2016. Oral Dysbiotic Communities and Their Implications in Systemic Diseases. Sudhakara et al, 2018. The oral microbiome: A Lesson in coexistence. Sultan et al, 2018. Frequency of Tongue Cleaning Impacts the Human Tongue Microbiome Composition and Enterosalivary Circulation of Nitrate. Tribble et al, 2019. The role of natural salivary defences in maintaining a healthy oral microbiota. Pedersen & Belstrom, 2018.

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