Dr. Indrė Stankevičienė / MF archive
“In science, it’s as it should be. We try to piece together a big picture using the very small pieces of a puzzle. Therefore, as a researcher, I do not have the desire to research and find out everything, or indeed, do it alone, without a team,” says Dr Indrė Stankevičienė, an odontologist at the Žalgiris Clinic of Vilnius University Hospital. She has defended her doctoral thesis entitled, “Dry mouth conditions: the epidemiological and clinical indicators and links with genetic, behavioural and stress factors” at the Faculty of Medicine this year. We talked to her about her thesis research.
How relevant is the dry mouth condition to society?
I had the opportunity to join a research team that organised a national oral health survey in 2017 to investigate the oral health of the Lithuanian population. The last time any general information on this topic was collected, was some 20 years ago. Our research team decided to repeat the survey. As there was no previous data on the prevalence of dry mouth conditions in Lithuania at all, I found it very interesting to look at this specific oral health problem. We did not know how many people might be affected by dry mouth, and it is a strong indicator of some oral diseases. All of this seemed very interesting to me, as a general practitioner, and worthy of research: what general conditions are the public suffering from, why are they suffering from it, and so on. The dry mouth condition has not been little studied in Lithuania. Most PhD students are orthopaedic dentists, surgeons, orthodontists, etc., and they are looking at very specific and narrow areas.
Why does dry mouth develop and what are the risk factors?
Dry mouth is known to be caused by various chronic diseases, the use of medications, psychological conditions (stress, etc.), and inappropriate lifestyles (bad habits such as smoking, alcohol consumption, etc.). In my thesis, I did not investigate the causal links, i.e. why dry mouth develops in the first place, but rather researched the number of dry mouth sufferers in Lithuania, with a view to developing and building preventive programmes, and identifying the risk factors associated with dry mouth. In other words, who the patients in Lithuania are and why some have more dry mouth manifestations and complications than others. The aim of my research was not to find out whether the factors mentioned in the title of the thesis – genetic, behavioural and stress-related – cause dry mouth, because it was already understood that they do, but rather, in what way does oral health depend on these factors. I analysed the interrelationships between these factors.
The research results showed that in Lithuania, as in the rest of the world, the percentage of people with strong or weak dry mouth symptoms is around 21%. This is a very high percentage – almost a fifth of the Lithuanian population. Meanwhile, 8% experience more serious forms of dry mouth, such as xerostomia (a subjective dry mouth sensation that only the person can feel, but doctors might not detect any clinical signs). From these more general results on dry mouth conditions, we then looked at specific forms of the condition: we found that 0.6% of the Lithuanian population experienced dry mouth and dry eyes. A total of 0.14% have a complex disease such as Sjogren’s syndrome (an autoimmune disease in which the exocrine glands that produce saliva and tears are affected), which produces signs of dry mouth. This may seem like a very small percentage of people, but dry mouth is not only an ominous sign of oral health, but also a sign of more serious health problems, or in other words, complex diseases. Basically, dry mouth only helps us to diagnose more serious diseases. For example, the diagnosis of Sjogren’s syndrome can take 3-6 years. This means that the patient has been unwell for a long time and has many clinical signs, both related to oral health and manifested by other health conditions, such as persistent coughing, itching, chronic fatigue, and damage to various organ systems. People may not understand what is happening to them, doctors may not find the disease. So, if doctors had a better understanding of dry mouth conditions, we could diagnose more serious diseases much more quickly.
Dr. Indrė Stankevičienė / MF archive
Can you tell us more about the link between genetic factors and oral diseases?
In fact, little is yet known about the influence of genetics on oral diseases. We are just starting to identify genes that might be linked to oral diseases. Therefore, we cannot yet speak of obvious causal links where the expression of a single gene leads to complex oral pathologies. We are looking for genes that are linked to oral diseases, to see how strongly they may affect oral health. In my thesis, I looked at a single gene and its copy number, i.e. how strongly variations in that specific gene predispose us to oral diseases and dry mouth. The results of the research were seemingly contradictory: a higher copy number of a particular gene coding for salivary alpha-amylase had a greater impact on the development of dental caries, but the same higher copy number was associated with a lower dry mouth sensation and a lower risk of Sjogren’s syndrome, which is a positive thing. This can be explained by plausible mechanisms of action, but we cannot yet draw any general conclusions. Our aim is to collaborate with researchers, to publish the results of our research, to look further into the results, to see how the expression of these genes works in other populations, whether this expression is different, and so on.
Apart from Sjogren’s syndrome, what other co-morbidities might be indicated by the presence of the dry mouth sensation?
Essentially, dry mouth should not be understood as an oral disease that develops because of some changes or damage in the mouth, but as a general indicator that the body is unhealthy. This means that people experience dry mouth if they are physically or emotionally unhealthy, i.e., their overall body condition is not good. Dry mouth can be caused by a chronic disease or medication. If a person takes several medicines at the same time, the risk of dry mouth increases several times. At the same time, the risk of complications from oral diseases (tooth decay, etc.) increases. If a person has a single condition, e.g. gastro-oesophageal reflux, an oncological disease, diabetes, emotional difficulties, etc., any of these and indeed, many other conditions, can lead to dry mouth. However, if, for example, a person is ill both with gastro-oesophageal reflux disease and diabetes mellitus, then dry mouth will be particularly pronounced. Dry mouth becomes an indicator of how well a person is controlling the underlying pathology. For example, in the case of diabetes mellitus, if the patient finds it difficult to control blood sugar, they may experience an exacerbation of dry mouth, whereas if control is good, their dry mouth will stabilise.
Dr. Indrė Stankevičienė / MF archive
How is dry mouth diagnosed?
Although it is difficult to say what exactly is causing the patient’s dry mouth in each case (many factors are involved), the diagnosis of the condition itself is fairly standard. First, we use a questionnaire. In this way, we can diagnose subjective dry mouth, like the xerostomia mentioned earlier. When answering the questions, the patient indicates that their mouth is sometimes or often dry. Next, we would test not the dry mouth sensation itself, but the amount of saliva (there is a standard amount that an adult should excrete in any given period). The patient is asked to spit into a tube and after about 15 minutes we can see whether there is enough saliva or not. In the case of a deficiency, the patient is classified as having hyposalivation. We identify other types of dry mouth by the presence of dry eyes (a very common accompanying pathology). In this case, if the person feels a deficiency of both saliva and tears, and a dry syndrome can be diagnosed (dryness not only in the mouth but also in the eyes).
However, we dentists do not diagnose Sjogren’s syndrome. If we suspect that a patient may have it, then we refer them to rheumatologists who, after various tests, add up the scores and determine if it is Sjögren’s. What is clear, is that it is not just dentists who should be involved in the management of dry mouth conditions. Close cooperation with rheumatologists as well as with doctors in other fields is required. However, often a visit to the dentist and a dry mouth diagnosis can be the first incentive for a patient to become concerned not only about their oral health, but also about their overall health, by being checked for a specific disease.
During the national survey, out of 1,500 randomly tested people in different regions of Lithuania, we identified eight people who had both dry eyes and dry mouth. Of these, two were diagnosed with Sjogren’s syndrome, another two had other chronic diseases, and still others, rheumatic diseases. The patients thought they were healthy before we noticed the signs of dry mouth. We referred them to specialists, who diagnosed specific chronic diseases that required appropriate treatment. It is very unfortunate that two patients who were referred to their GPs were discouraged by them from having their condition examined further. This indicates a certain lack of education among physicians about the seriousness of dry mouth conditions. It is not enough for us dentists to be very knowledgeable about these conditions and to educate each other. We need the involvement of doctors from other disciplines.
Additionally, dry mouth is certainly not just a health problem in older people. In my practice, I have certainly had young patients with gastroesophageal reflux (acids from the digestive tract entering the mouth and causing dry mouth), or with emotional difficulties that caused dry mouth. Certain signs may lead us to suspect diseases that patients have already been diagnosed with. For example, when we notice dry mouth and ask the patient if they have diabetes, they often confirm this previously diagnosed condition. The problem is that patients do not know that it is not only the control of the existing disease that is important, but also the risk of complications from accompanying oral conditions.
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What steps should be taken to prevent dry mouth?
There are practically no effective treatments for dry mouth (some of the drugs used worldwide have a lot of side effects and are therefore not very common in Lithuania). There are only symptom-relieving measures (various saliva-inducing sprays, creams, tablets, or the patient is put on a diet of fibrous foods that encourages more chewing and thus stimulates the saliva glands). Prevention therefore plays a very important role. If a person follows the general principles of a healthy lifestyle – exercises, eats a proper diet (avoiding tobacco, alcohol and coffee), maintains emotional health, and is active in cardiovascular and endocrine disease prevention, the risk of dry mouth is reduced. If these principles are not followed, then the likelihood of chronic disease develops, and with it not only dry mouth, but also other oral and dental diseases (active caries, etc.). And if a chronic disease (rheumatic, autoimmune, etc.) is already present, it is important to be able to control it with the help of specialists or medication, which can also significantly reduce dry mouth. The main “cure” is therefore to lead as healthy a lifestyle as possible and to control chronic diseases.