Updated: Oct 21
In the previous article, I introduced the topic of dental health in relation to broader health. We talked about why dental health is essential, about the oral microbiome and its effects on oral health, as well as how disturbed microbiome can effect oral health in a negative way.
In part 2 I'll share with you how poor dental health may impact the rest of the body, including the whole cardiometabolic system, the digestive system and the brain. We'll talk about potential mechanisms (for those of you who are a bit geekier) that may be going on in the background. And then in part 3 we'll get more into practicalities and talk about ways to protect our dental health to stay away from health problems.
As always, there is also a short summary towards the end for those short on time so if you're not too interested in reading the whole thing, just head to the Summary section.
Before we get into this
One thing I want to emphasise is that nearly all of the studies I have reviewed to write this article are observational studies. Compared to interventional studies (such as placebo trials) observational studies do not have the power to make correlations (e.g. exposure to A causes B). Observational studies can only show associations (e.g. many people exposed to A also have B, but we need interventional studies to show the direct correlation because B could also be caused by exposure to C, D, E and K). Unfortunately, for the type of research, I'll be reviewing we'll never have interventional studies because they would be unethical. Researchers cannot conduct studies that would try to give people periodontal disease and then see if these get disease seeming from that. And so observation (looking at people who do something and seeing what happens without intervening) is the best evidence we have.
So just be mindful of all this as you read. Of course, some types of observational studies have more punching power than others, but overall, nothing I write here is to be mistaken for causality or correlation.
Untreated, periodontal disease predisposes people to a variety of cardiovascular (heart & the veins) problems.
One of the potential issues is infective Endocarditis (IE), a dangerous bacterial infection of the inside structure of the heart. This occurs when bacteria get into the bloodstream and then attach to the heart while the blood is being pumped through. As you may recall from part 1, one of the risks of long-term untreated dental infection is that bacteria form biofilms; the huge colonies sitting under the infected tooth can enter the bloodstream and circulate around the body. When that happens, the chance is that some of the circulating bacteria will attach to the heart and an infection may start to spread before they are destroyed by the immune system. Some early research has found that about 8% IE cases are potentially caused by dental infection. Unfortunately, in this area, the research we have available is not very sufficient.
Another risk area is stroke. You could say that stroke is a "heart attack of the brain". During stroke episodes, there is a temporary obstruction of the artery inside the brain or one of the major arteries supplying the brain with blood. When this happens, portions of brain matter could be destroyed, possibly resulting in permanent disability and often death. Common risk factors for stroke are diet high in salt, saturated fats, smoking, high alcohol consumption and physical passivity. Additionally, we have some research that has shown association to dental disease as well.
A study from Malmo, Sweden has found that people with the highest rate of periodontal disease had the worst progression of plaque deposit inside the arteries supplying the brain. Other studies show that people who have experienced stroke often have worse dental health compared to those who were stroke-free. A variety of animal studies are supporting these findings as well. Of course this does not mean "periodontal disease causes stroke"; however it means that those with periodontal disease are statistically at increased risk of early stroke than those without.
Type 2 diabetes is a disease of blood sugar metabolism. The body of type 2 diabetic has developed a resistance to the hormone insulin and is no longer responding to its signals to take glucose into the cells. This is a considerable issue because glucose, if kept around in the circulation for too long, may gradually damage blood vessels as well as many fragile organs such as eyes, kidneys and extremities. A poorly managed diabetes may, over decades, lead to amputations, heart disease, kidney failure and even Dementia.
In terms of dental health, a small amount of preliminary research is showing that when dental health problems such as periodontal disease are properly treated, diabetes may improve as well. It has been shown that people with ongoing diabetes are at 86% increased chance of developing periodontitis, a systemic dental disease characterised by the inflammatory destruction of the tooth-supporting tissues, including the bone and the root of the tooth as well. We also have one large systematic review of interventional trials which shows that when diabetics who also had periodontal disease had undergone a dental treatment and had the oral disease treated, their systemic markers of blood sugar balance improved significantly. And this is a major finding from a high-quality research study.
What's the mechanism with diabetes (for geeks)
During prolonged exposure to high amount of sugar inside the blood, variety of proteins and lipids that are also in the circulation start getting damaged and biproducts called AGEs (Advanced Glycation End Products) are created. AGEs are highly inflammatory on the systemic level and can trigger processes that can gradually damage tissues and organs. This includes the kidneys, the eyes, the brain and may theoretically also include the oral health.
[sub-chapter continues here] It is also known that hyperglycaemia (high blood sugar levels) can alter and damage gingival microvasculature (tiny vessels supplying our gums with blood, oxygen and nutrients), which can lead to periodontal inflammation and gradual distraction of the apparatus that keeps the tooth locked inside the gum.
The final disease from this subchapter is metabolic syndrome (MeS). MeS is a cardiometabolic condition characterised by 5 key features out of which the patient has to present with 3 or more to be diagnosed with MeS. The 5 defining features are:
"waist circumference over 40 inches (men) or 35 inches (women),
blood pressure over 130/85 mmHg
fasting triglyceride (TG) level over 150 mg/dl
fasting high-density lipoprotein (HDL) cholesterol level less than 40 mg/dl (men) or 50 mg/dl (women)
fasting blood sugar over 100 mg/dl."
We have a few interesting studies that show the following relationship between oral health disease and metabolic syndrome
The more periodontal pockets (deep inflamed gum tissue under a tooth) people had, the higher the likelihood of also having metabolic syndrome
Brushing one's teeth at least 3 times a day was associated with a lower rate of metabolic syndrome compared to those who brushed less.
Vice-versa, Japanese studies showed that those with an already diagnosed periodontal disease were 260% more likely to develop a metabolic syndrome within 3 years compared to those without periodontal disease
In a long-term observational study, 683 men were followed from 1981 until 2013 as a part of Dental Longitudinal Study. These men had undertaken several dental check-ups over those years to see a progression of any dental disease but also other diseases such as metabolic syndrome. After the 2013 examination, the researchers have observed some interesting findings among these people:
Men diagnosed with MeS had more tooth loss, more bleeding upon examination, more destruction of alveolar bone (a tiny bone holding the tooth in the socket), more periodontal pockets (deep pockets of inflammation) as well as more tooth mobility upon probing
Men not diagnosed with MeS had significantly less of nearly all of the above
Together the findings in this chapter show some very strong association (not correlation) between poor dental health and the occurrence of certain cardiometabolic diseases. Like we said in the beginning, none of these means that A causes B. It does not mean periodontal disease causes stroke nor diabetes, nor metabolic syndrome. What this means is that people who have periodontal disease are also more likely to have (or to develop in their lifetime) one or more of these conditions or are (statistically speaking) at increased risk of developing these compared to people whose dental health is good. Of course, this may come down to other factors such as diet & lifestyle, none of which are controlled in observational studies but then it is safe to say that poor dental health is often an indicator of poor diet and often suboptimal lifestyle with the exception of rare genetic disorders.
Dental Health & Digestive System
As we previously discussed, the oral cavity (mouth) is where our colonies of the oral microbiome reside. It is also the area of the first contact with the outer environment. The oral cavity then leads down two ways. Either into trachea and the lungs via the respiratory system or into the, oesophagus and stomach via the digestive system.
Firstly, a major problem in people with progressive periodontal disease is the existence of Subgingival biofilms, highly-concentrated colonies of bacteria that endlessly multiply around the area of the infected tooth. Biofilms are an endless source of something we call LPS (lipopolysaccharides), toxic bi-products of certain harmful bacteria. LPS are highly toxic in greater amounts. Once they successfully migrate either through the bloodstream or down the digestive tract, they can create intra-intestinal inflammation, can damage the microbiome, cause a variety of digestive problems as well as migraines, mood problems and even conditions likes asthma or allergies. Naturally, stomach acid should protect against these, but many people suffer from insufficient stomach acid and many are also put on a type of medication called PPI (proton pump inhibitor) which block 90% of gastric acid production and so these people lose an important protector of the intestinal health and balance.
Secondly, a small amount of studies have shown that imbalances in the oral microbiome may cause a shift in the balance of the intestinal microbiome further down the digestive tract and cause an increase in the inflammatory response in this area. This might be a result of the LPS migration as mentioned above but it could also be a result of long-term chronic inflammation inside the mouth that has now spread wider into the rest of the body. I've touched on this topic in my two part series on Gut-Brain connection and if gut microbiome connection to wider health (especially mental health) interests you I highly recommend you check those out.
And so despite the fact that we are missing a larger, more statistically significant studies that would show a direct relationship between dental disease and digestive disease, based on the above, there exists a sufficient amount of early information that should prompt doctors to at least have patient's dental health invested by a dentist where digestive diseases are diagnosed and treated. People with chronic digestive problems such as SIBO, IBS, IBD, chronic constipation, diarhoea, haemorrhoids and other should also have their dental health properly checked by a dentist or hygienist to ensure the cause of those is not coming from the mouth.
Dental Health & Cognitive Health
Dementia is the most common cause of the cognitive decline in the world. The most common form of Dementia is called Alzheimer's Disease. It is estimated that by 2030, 82 million people will be diagnosed with Dementia incurring a total annual cost of $2 trillion dollars. Compared to previous conditions, there is significantly more research done on the topic of Dementia & periodontal research, which naturally makes it somewhat harder to interpret.
As of today, the data we have available on this topic is largely conflicting. Some of the largest studies show that periodontitis and periodontal disease, as well as tooth loss, are likely associated with Dementia, while many others show there is no association.
I won't go into trying to analyse every single study because it would bore the reader to death and secondly, I do not feel confident to try to make my own interpretation of the available data, at least not with my current level of research understanding. I would need to discuss these results with someone more versed in research interpretation.
My takeaway from the literature on cognitive decline and oral health is the following:
Because some studies are still showing positive association, I am inclined to believe that there is a positive relationship here albeit small or only mildly significant
We know that Alzheimer's disease risk is increased for people with diabetes and ongoing cardiovascular disease because, in a way, they are part of the same condition, which is gradual, systemic inflammation of the vascular system.
Because we have other studies (listed earlier) that show a very strong association between dental health and cardiometabolic disease, I would assume that poor dental health is a potential factor that can contribute to worsening cognitive performance in people who already have a degree of other health problems (such as diabetes or obesity or heart disease)
However, it would be hasty to say there is a correlation. There is not, at least not yet. And so, as of today, we cannot claim with certainty that a strong relationship exists between dementia and dental disease.
SUMMARY & KEY POINTS
A large amount of observational research is showing a positive association between periodontal disease and a variety of systemic conditions
Infective Endocarditis - a dangerous bacterial infection of the inside of the heart. It is possible that up to 8% of cases of this condition could be driven (or contributed to) by dental infection
Stroke – it has been found that many people who have experienced a stroke in their lifetime also have a poor dental health and wise versa; some research shows that people with the most progressed dental disease often have the most significant progression of plaque deposit in the arteries supplying the brain (this is major risk factor for stroke). This does not mean periodontal disease causes stroke but it shows a possible association of dental disease being a contributor to the onset of this condition.
Diabetes – small amount of studies show that when diabetics with ongoing periodontal disease (PD) received dental treatment and had their PD treated, their markers of diabetes improved. People with type 2 diabetes diagnosis are also more likely to develop the periodontal disease in their lifetime by up o 86% compared to people who are not diabetic.
Metabolic syndrome – various research trials show a positive association between poor dental health and increased metabolic syndrome risk. People with the most progressed MeS are also more likely to have mor significant dental inflammation. Dental assessment should be recommended and administered to all patients (alongside radical lifestyle & dietary therapy) with MeS as it is likely that in many, this will be a significant contributor to the onset of the condition.
Digestive disease – This section is based mostly on theory and speculation. We have very little research on humans to show that periodontal disease could be associated with digestive disease. When you read this section, read it with a healthy dose of scepticism because there is a lot of speculative mechanistic reasoning not verified by studies in humans.
Cognitive decline – compared to above, we have a lot of human studies studying the relationship between Dementia and periodontal disease; however they are highly inconclusive. Personally, I believe there is some association here; however it would require advanced knowledge of statistics and research interpretation to make sense of these studies, which I currently do not have.
Regardless of how convincing or statistically strong these studies are, poor dental health clearly goes beyond just smelly breath and bleeding gums. Each of us should do our absolute best to take excellent care of our teeth and gums. When in doubt, go see a dentist and get a hygienist checkup at least once a year. The couple hundred dollars this will cost is nothing compared to the cost of becoming severely sick in 20 years.
In the part 3, we'll go through some of the strategies how to protect your dental health through diet, lifestyle and some other practical tips. So stay tuned.