This week we’re taking a slight deviation from our usual content to examine something that most rarely think about aside from the two or so minutes we spend brushing our teeth each morning. Oral health is one of those topics that doesn’t get a ton of attention on the prevention front but is actually intricately linked to our overall health.
Because of this, we decided to take a deeper dive into the links between oral health and overall health particularly as it relates to systemic inflammation and age-related disease.
This is what we found.
The Mechanism of Gum Disease
Periodontal disease (gum disease, periodontitis) is a collection of inflammatory conditions affecting the tissue and supporting structures around the teeth. Despite the push for oral hygiene practices like tooth brushing and flossing by public health entities and big corporations, gum disease is common even among young people. In fact, the CDC estimates that 46% of adults over 30 show some sign of gum disease (e.g., bleeding, swollen, or receding gums, halitosis, deep pockets between the teeth and gums); the number increases further among older adults, with approximately 70% of adults over 65 having some form of periodontitis.
Gum disease occurs in four stages:
- Gingivitis—inflammation of the gum tissue
- Mild periodontitis—beginning of bone and tissue loss around the teeth
- Moderate periodontitis—progressing loss of bone and tissue around the teeth
- Advanced periodontitis—extensive bone and tissue loss, loosening of teeth and/or tooth loss
Of the four stages of gum disease, gingivitis is the only stage that is reversible with improved hygiene practices, regular dental cleanings, and dental treatments (e.g., deep cleaning and scaling) when necessary. Once you’ve crossed into mild periodontitis, prevention is no longer an option. The main aim becomes minimizing damage so the disease doesn’t progress any further.
While some conditions put you at risk for developing gum disease (e.g., diabetes), its primary cause is poor oral hygiene; we aren’t just talking regular tooth brushing, flossing your teeth and having regular dental exams is included as good oral hygiene practice. If you neglect one or more of these habits, you put yourself at risk for gum disease. Other risk include poor nutrition and smoking, but hygiene is the most important.
The mechanism underlying gum disease occurs in relation to the oral biome. Failure to properly brush and floss the teeth allows bacteria to form plaque on the teeth as well as at or below the gum line. As plaque accumulates due to poor oral hygiene, it disturbs the normal oral biome and triggers an immune response as your body tries to eliminate the bad bacteria. This immune response can result in red, swollen, or bleeding gums in the beginning stages, but if left untreated, will progress to a more severe immune response. This can cause the destruction of bone and surrounding structures that keep the teeth in their sockets.
Oral Health and Systemic Diseases
Gum disease isn’t the only consequence of poor or incomplete oral hygiene. A number of other systemic conditions have been linked to oral health, some of which surprised us. We took a deep dive into some of the studies that examine these links to get a better understanding of how oral health can lead to three major age-related diseases.
One of the major disease processes that continually showed up in the review papers we read was CVD. As the number one cause of death in the US for both men and women, we definitely think it’s worth taking a closer look at the ways oral health interacts with the cardiovascular system. For example, this meta-analysis of 5 cohort studies (N=86,092) showed that individuals with gum disease are 1.14 times more likely to develop coronary heart disease than controls; furthermore, the same meta-analysis found an even great risk among case control studies suggesting that the risk may be as much as 2x higher in individuals with gum disease. In this instance, the magnitude of the risk, whether 1.14 or 2, is almost irrelevant. The real information to glean from these studies is that gum disease puts individuals at a significantly higher risk for developing heart disease in the future independent of dietary factors.
A similar pattern has been found in heart disease complications. For instance, this study of arterial plaques found bacteria common to the oral biome inside of the plaques, suggesting a migratory effect of oral bacteria into the bloodstream. Gram-negative bacteria like Porphyromonas gingivalis (P. gingivalis) are known to promote clot formation which can lead to a heart attack or stroke when it occurs in the arteries.Case-control and cross-sectional studies have both shown an association of gum disease with stroke risk. This study of 40 stroke patients and 40 randomly selected healthy controls matched for sex and age, found that poor oral health was more common in the stroke patients than in controls. Similarly, this study showed that oral health conditions were significantly associated with the diagnosis of stroke regardless of risk status.
The mechanisms for how gum disease increases the risk of CVD remain unclear despite strong evidence to show that gum disease can predispose an individual to atherosclerosis, heart disease, and assorted complications like heart attack and stroke. We did find this article that sets forth several possible mechanisms for how oral health may directly or indirectly influence CVD pathology.
Source: Li, X., Kolltveit, K. M., Tronstad, L., & Olsen, I. (2000). Systemic diseases caused by oral infection. Clinical microbiology reviews, 13(4), 547–558. https://doi.org/10.1128/CMR.13.4.547
Of the hypothesized mechanisms in the diagram, four of the five suggests that the presence of bacteria or inflammatory products in the bloodstream causes a hyperimmune response. This response indirectly affects heart disease pathology either by: 1) increased platelet aggregation, 2) increased C-reactive protein (CRP) deposits in the blood vessels, or 3) increased inflammation caused by immune cell hyperactivation. The diagram (and paper) also suggests a fifth more traditional and direct link between gum disease and CVD. At the end stages of gum disease, individuals are likely to experience tooth loss; this alters their ability to consume certain foods, particularly fiber rich grains, fruits, and vegetables. In turn they are left to consume foods high in solid fats that increase their risk for atherosclerosis and CVD complications.
Diabetes is another condition extensively linked to oral health, though not in a way you might expect. In fact, gum disease isn’t a causative factor in diabetes pathology, but it can make it harder to treat and can predispose an individual to diabetic complications. Part of the body’s immune response is to increase glucose availability in the bloodstream so that the cells can use it to destroy pathogens. Diabetics already have difficulty controlling their blood sugar, so when a diabetic develops gum disease, the result is often poorer glycemic control due to the underlying immune response. Consistently high blood sugar puts diabetic patients at risk for complications like blindness, neuropathy, and kidney disease.
At the same time, diabetes also impairs wound healing, making the likelihood that gingivitis will progress into periodontitis more likely. For instance, this study found that diabetics are 3x more likely to develop gum disease than their non-diabetic counterparts. This study underscores the health effect of poor wound healing associated with diabetes, but also suggests that diabetes may act as an accelerant for gum disease. Other studies have shown that while diabetics are at greater risk for developing gum disease, the presentation of their disease is proportional to the amount of time they have been diabetic. Essentially, the longer a person has been a diabetic, the more likely they are to have severe gum disease.
A few possible mechanisms have been proposed for how gum disease and diabetes may interact to cause larger scale systemic effects. One hypothesis we found suggests that gum disease upregulates the production of inflammatory markers due to chronic exposure to bacterial products like lipopolysaccharides. In turn, this amplifies the advanced glycation end product-mediated (AGE-mediated) immune response. AGEs are known to increase inflammation and oxidative stress, so the presence of gum disease in diabetics is essentially doubling down on the inflammatory response. The authors of this model suggest that this 2-way mechanism may explain why gum disease is so much more severe in diabetics compared to non-diabetics.
While heart disease and diabetes are plausible, the link between oral health and Alzheimer’s is less obvious. To date, research has attributed a multitude of factors to Alzheimer’s Disease, yet oral health is often left out of the conversation despite evidence to the contrary. Alzheimer’s is a type of dementia characterized by progressive loss of memory, thinking, language, and learning ability. Alzheimer’s is irreversible and eventually leads to a loss of function and death.
One of the risk factors attributed to the disease is infection and like the other age-related diseases we reviewed, the underlying factor connecting gum disease and Alzheimer’s is inflammation. When a person has gum disease, they continuously produce inflammatory markers as part of the immune response. While the brain was once thought to be protected against immune responses, this study suggests that the brain is indeed vulnerable to certain immune processes like complement system activation. The brain is also subject to the innate immune response which tries to clear beta and tau amyloid plaques from the tissues, though it only further aggravates the condition. With this in mind its fairly easy to make the jump between gum disease and Alzheimer’s. In fact, products from gum disease pathogens have been found in Alzheimer’s brains during post-mortem examinations, further underscoring the idea that inflammation caused by a hyperactive immune response connects the two diseases. Additionally, bacterial species (C. pneumoniae and T. denticola) have also been found in Alzheimer’s brains, suggesting that not only do gum disease pathogens act as mediators of the immune response, but can also cross into the brain tissue and cause further damage.
Source:Bui, F. Q., Almeida-da-Silva, C., Huynh, B., Trinh, A., Liu, J., Woodward, J., Asadi, H., & Ojcius, D. M. (2019). Association between periodontal pathogens and systemic disease. Biomedical journal, 42(1), 27–35. https://doi.org/10.1016/j.bj.2018.12.001
In addition to these three major age-related diseases, gum disease has been linked with other systemic non-oral disease processes from certain types of cancer to depression to pregnancy outcomes in expectant mothers. Check out these articles on other systemic processes that are affected by oral health:
- Periodontal Disease, Tooth Loss, and Cancer Risk
- Poor oral hygiene as a risk factor for infective endocarditis–related bacteremia
- Genetic relationships between Candida albicans strains isolated from dental plaque, trachea, and bronchoalveolar lavage fluid from mechanically ventilated intensive care unit patients
- Persistently high levels of periodontal pathogens associated with preterm pregnancy outcome
- The association of depression and anxiety with dental caries and periodontal disease among Finnish adults
Based on what we found in our research on this topic, the common denominator between age-related diseases and gum disease is underlying inflammation. Admittedly, there’s not much we can do about our innate immune responses, but there are things we can do to reduce our risk of developing gum disease as well as things we can do to keep our immune systems healthy. Practicing good oral hygiene like brushing twice a day, flossing, and getting regular checkups is top of mind when it comes to oral healthcare, but if you’d like to enhance your efforts you may consider adding a fluoride containing product to your routine if your toothpaste doesn’t already have it as an ingredient. As far as immune health goes, we have our most obvious, basic health principles like eating a diet with lots of fruits and vegetables, getting exercise, getting enough water, and getting good quality sleep. Using these principles together will keep your body and your teeth in top shape.
Additional Resources on Oral Health
- National Institute on Aging: Taking Care of Your Teeth and Mouth
- Find A Dental Professional
- Comprehensive List of Oral Health Studies
- CDCPeriodontal Disease and Diabetes Podcast
- Chemotherapy and Oral Care
- Turning Back The Clock on Gum Disease
- Researchers Identify Immune Culprits Linked to Inflammation and Bone Loss in Gum Disease
- Genes Are Key to Oral Health & Beyond
Were you surprised to learn about the link between oral health and age-related diseases? Share your thoughts with us: email@example.com
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