World Stroke Day: While high blood pressure, diabetes, and smoking are well-known risk factors for stroke, scientists are now drawing attention to an often-overlooked contributor—poor oral health.
A new study published in the official journal of the American Academy of Neurology, Neurology, reveals that people suffering from both gum inflammation and dental cavities face an 86 per cent higher risk of ischaemic stroke—the most common kind of stroke caused by the blockage of a blood vessel— compared to those with healthy mouths. The findings suggest that maintaining oral hygiene may play a more crucial role in preventing life-threatening conditions than previously understood.
These findings are of particular significance as globally 1.5 crore people suffer from strokes annually, and the burden in India is also significant. Considering this alarming rate, it becomes vital to understand what a stroke is, how it occurs, and how poor oral health can increase the risk. The new study also invites a broader discussion on the scale of oral diseases and how experts are weighing in on this emerging connection between oral and cardiovascular health.
What is an Ischaemic Stroke?
A stroke is essentially a life-threatening medical condition that occurs when the blood supply to the brain is cut off. When the blood supply to the brain is cut off, it does not get oxygen either, and the brain cells essentially die within minutes, causing a stroke.
When brain cells die due to a lack of oxygen, patients can suffer from long-term disability or even death, depending on which area of the brain is affected. The sooner a stroke is detected and treated, the greater the chance of recovery, making early intervention critical.
Now, depending on how the blood supply is interrupted, strokes are classified as ischaemic or haemorrhagic.
“A haemorrhagic stroke or bleeding stroke happens when a blood vessel bursts suddenly, causing blood to leak in or around the brain. In this kind of stroke, blood in the brain can lead to swelling of the brain, which requires surgery in some cases. Bleeding stroke is most commonly seen among people with high blood pressure (hypertension),” according to the WHO.
However, this kind is comparatively rare. An ischaemic stroke, which occurs when the blood flow to a part of the brain is blocked by a blood clot or buildup of fatty deposits in the arteries, is the far more common kind of stroke. Different sources estimate that anywhere between 80 and close to 90 per cent of all strokes globally are ischaemic strokes.
What are the symptoms?
Symptoms of ischaemic stroke vary, but commonly include sudden weakness or numbness on one side of the body, difficulty speaking or understanding speech, facial drooping, vision problems, dizziness, loss of balance, confusion, or a severe headache.
Recognising these warning signs quickly can be lifesaving, which is why health experts recommend remembering the acronym BE FAST—Balance, Eyes, Face, Arms, Speech, and Time. Any sudden loss of balance, blurred vision, drooping face, or slurred speech should be treated as a medical emergency.
How is it caused?
The primary cause of ischaemic stroke is ischaemia, a condition in which brain cells die due to insufficient blood flow. The most frequent culprit is a blood clot obstructing circulation in an artery. Underlying conditions such as atherosclerosis, high blood pressure, high cholesterol, atrial fibrillation, type 2 diabetes, and clotting disorders can all increase this risk. Smoking, alcohol use, sedentary lifestyles, and even certain viral infections such as COVID-19 further elevate the likelihood of developing an ischaemic stroke. Older adults, individuals with a family history of stroke, and those with uncontrolled hypertension remain among the most vulnerable groups.
How common are strokes?
According to the WHO, annually, about 1.5 crore people suffer from strokes across the world. “Of these, 5 million die and another 5 million are left permanently disabled, placing a burden on family and community,” according to the organisation.
“The incidence of stroke is declining in many developed countries, largely as a result of better control of high blood pressure and reduced levels of smoking. However, the absolute number of strokes continues to increase because of the ageing population,” it added.
According to the World Stroke Organization: Global Stroke Fact Sheet 2025, strokes cost approximately 0.66 per cent of the global GDP, or over 890 billion US dollars. It also highlighted that the number of stroke cases were also rising between 1990 and 2021. There has been a 70 per cent increase in cases and a 44 per cent increase in the number of deaths from strokes. It says that 1 in 4 people will have a stoke in their lifetime.
In India, too, stroke remains a significant concern. According to data from India’s National Stroke Registry Programme (NSRP), the country reports between 119 – 145 stroke cases per lakh population annually, with around 86.5 deaths per lakh due to stroke each year. This translates to an estimated 14.4 to 16.6 lakh new stroke cases annually.
Scenario in India
This stroke burden in India has been rising sharply. An analysis published in The Lancet Neurology revealed that India has witnessed a staggering 51 per cent increase in stroke cases between 1990 and 2021.
In fact, the government launched the National Programme for Prevention and Control of Cancer, Diabetes, Cardiovascular Diseases and Stroke (NPCDCS) in 2010, “with focus on strengthening infrastructure, human resource development, health promotion, early diagnosis, management and referral” to help address the growing risk of such non communicable diseases in the country.
A Lok Sabha reply stated that “the Department of Health & Family Welfare provides technical and financial support to the States/UTs under the National Programme for Prevention and Control of Non-Communicable Diseases (NP-NCD), as part of National Health Mission (NHM), based on the proposals received from the States/UTs and subject to the resource envelope. Stroke is an integral part of NP-NCD.” The programme, it added, aims to strengthen healthcare infrastructure, train medical personnel, and promote awareness for early diagnosis and management.
The ministry noted that stroke is a multifactorial disease, influenced by hypertension, diabetes, sedentary lifestyle, smoking, alcohol consumption, and poor diet. To tackle these, preventive activities have been expanded under the Ayushman Arogya Mandir scheme, which focuses on wellness promotion and targeted communication at the community level. Awareness initiatives include the observation of World Stroke Day and consistent messaging through print, electronic, and social media.
Further, the government provides financial assistance to States and UTs under the NP-NCD for awareness campaigns through their Programme Implementation Plans (PIPs). Stroke treatment is being made accessible through district hospitals, medical colleges, and premier institutions like AIIMS, with care being free or highly subsidised for poor and needy patients. As of now, stroke services under the NP-NCD are operational in 19 States, reflecting a gradual but significant step toward integrating stroke care within India’s public health system.
What the study found
The new study, conducted by scientists at the University of South Carolina, sought to examine whether oral infections could contribute to the risk of ischaemic stroke. It focused on two common dental problems—cavities and periodontal (gum) disease. Cavities develop when acid-producing bacteria erode the enamel on teeth, while gum disease is a chronic inflammatory condition caused by bacterial plaque that damages the tissues supporting the teeth.
The study analysed data from nearly 6,000 middle-aged adults who had no previous history of stroke. Each participant underwent a dental examination and was grouped into one of three categories: those with healthy oral health, those with gum disease alone, and those with both gum disease and cavities. They were then followed over several years to track any occurrence of stroke. The findings revealed that 4 per cent of participants with healthy teeth experienced a stroke, compared to 7per cent among those with gum disease and 10 per cent among those with both gum disease and cavities. This clearly showed that the combination of both conditions amplifies the risk of stroke far more than either alone.
“After adjusting for factors such as age, body mass index and smoking status, researchers found when compared to people with healthy mouths, those with both gum disease and cavities had an 86% higher risk of stroke. Those with gum disease alone had a 44% increased risk,” (sic.) according to the press release by the American Academy of Neurology, in whose journal the study was published.
Another significant finding of the study was the protective impact of regular dental care. Participants who visited dentists routinely for professional cleaning and treatment had an 81 per cent lower likelihood of developing both cavities and gum disease. This suggests that preventive care and timely intervention can play a major role in mitigating stroke risk associated with poor oral hygiene.
However, they also cautioned that factors such as socioeconomic status, diet, genetics, and access to healthcare could influence outcomes, and therefore more longitudinal studies are needed before establishing a direct cause-and-effect relationship.
But how is oral health linked to stroke?
Researchers believe the mechanism behind this link lies in the entry of oral bacteria and their toxins into the bloodstream. Once inside, they can trigger chronic inflammation, which promotes the formation of blood clots that block blood flow to the brain—a defining feature of an ischaemic stroke. Over time, this inflammatory process can weaken blood vessels and contribute to cardiovascular and neurological diseases.
This is significant as globally, oral diseases are among the most widespread non-communicable diseases, affecting nearly 370 crore people, according to the World Health Organisation (WHO). These include tooth decay, gum disease, oral cancer, tooth loss, and developmental conditions such as cleft lip and palate. Tooth decay occurs when bacterial plaque interacts with sugars from food and drinks, forming acids that gradually erode the tooth’s protective enamel. Poor oral hygiene, excessive sugar consumption, and limited fluoride exposure worsen the condition. Similarly, periodontal disease, which affects the tissues around the teeth, leads to gum swelling, bleeding, bad breath, and eventual tooth loss. More than one billion people globally live with severe gum disease, facing both physical pain and emotional distress.
Implications of poor oral health
The impact of poor oral health extends far beyond the mouth. Chronic gum inflammation has been linked not only to stroke but also to heart disease, diabetes, respiratory infections, and adverse pregnancy outcomes. This growing understanding that oral health mirrors systemic health highlights why it deserves greater public attention and policy focus.
In India, the challenge is both extensive and under-addressed. As per the WHO’s Oral Health Country Profile 2022, untreated dental caries affects 43.3 per cent of children and 28.8 per cent of people aged five and above. Severe gum disease impacts 21.8 per cent of adults, while 4 per cent of the population has lost all teeth.
Contributing factors include tobacco use among 28.1 per cent of the population, alcohol consumption of 5.6 litres per person per year, and high sugar intake of 53.8 grams per day. Combined with limited access to dental care and low healthcare spending, India’s oral health crisis remains a silent epidemic.
What experts say
Dr Viswanathan Iyer, Neurosurgeon at Zynova Shalby Hospital, Mumbai, commented on the study linking oral health and stroke, noting that India faces significant challenges regarding oral hygiene. He observed that habits such as betel nut chewing and poor dental care make oral health a widespread issue in the country. According to him, “while dental cavities and gum health can contribute to overall health, they are not the primary focus when assessing stroke risk.”
Dr Iyer emphasised that in India, stronger risk factors like hypertension, diabetes, obesity, tobacco use, smoking, sedentary lifestyle, and poor diet play a much larger role in stroke occurrence. He stated, “Good oral hygiene is certainly important, not only for preventing dental issues but also as a preventative measure for other diseases such as heart disease and oral cancers. Conditions like oral submucous fibrosis, often caused by betel nut chewing, can make mouth opening difficult and are known precursors to oral cancer.”
Regarding the study’s caution about socioeconomic status, diet, genetics, and access to healthcare influencing outcomes, Dr Iyer suggested that the observed association between poor oral hygiene and stroke may be influenced by broader social determinants of health. He explained, “I have a feeling this could be more like a causal association. Many individuals from lower socioeconomic backgrounds with less education and limited access to clean facilities may also have poor oral hygiene, undernutrition, and limited knowledge about stroke risk factors. This makes it difficult to directly link dental hygiene to stroke at this stage.”
On practical measures for oral care, Dr Iyer recommended following traditional good practices, noting, “Brushing twice a day, flossing daily, avoiding sweets an hour before bedtime, and at least annual dental check-ups, especially after the age of 35-40, are essential steps everyone should follow.”
This story is done in collaboration with First Check, which is the health journalism vertical of DataLEADS.