Let's Talk Oral Health
Let's Talk Oral Health is an expert podcast designed specifically for oral health professionals. This first season brings together experts from around the globe to discuss the latest trends in preventing periodontal and peri-implant diseases. LTOH is your go-to source for dental research topics, practical insights, and interviews featuring top professionals in the field.
Let's Talk Oral Health
Expert Q&A: Mastering the Oral Microbiome
Prof. Egija Zaura tackles all your inquiries about the complications of microbiome imbalance and its significant influence on oral health and diseases like periodontitis.
This is let's Talk Oral Health the expert podcast for oral health professionals brought to you by Sunstar.
Speaker 1:Hello everyone, Welcome to let's Talk Oral Health Expert Series by Sunstar. My name is Rachel and this is the Q&A session following the episode we held on the oral microbiome-driven approach in a 360 strategy to prevent periodontal and peri-implant diseases. We gathered the questions we received in the past few weeks to be answered directly by the guest of our episode, Professor Egea Zahra. Hello, Egea, welcome back.
Speaker 2:Hello Rachel, good to see you again, good to see you as well.
Speaker 1:We are delighted to have you back with us to answer to some questions that were stirred up by our conversation. We will discuss some of them exactly as I came in, while others being a bit similar, we decided to group them together, so let's dive right into it. With the first question. You said during our conversation that antimicrobials should be avoided in healthy patients. Some patients are not always efficient with just a daily mechanical cleaning. What would you recommend then?
Speaker 2:Well, thank you for the question. I would rather think if somebody is not able, mechanically, to do the good mechanical cleaning, then there is already something for me indicating that this is not completely healthy situation. So I would first check uh, what is here wrong? Is the person really unable to brush better, meaning that there is some handicap, maybe a disease or maybe a broken shoulder can happen, but maybe it's just somebody who doesn't know how to brush well, and I would then first invest in educating and showing and trying to train this person to do better mechanical cleaning. If there is a physiological reason for maybe temporary, that somebody is ill and cannot do mechanical cleaning that well, then of course there is an indication for antimicrobial help.
Speaker 2:So, yes, there are exceptions when you should do something to help patients to get rid of this biofilm if mechanical cleaning is really not possible. But I would certainly focus on improving mechanical cleaning. Also, when somebody is in the hospital, it's still possible for nurses or for family to help and to do mechanical cleaning for the patient who is unable to clean themselves. The same goes for elderly homes. We should be able to help and to clean these mouths.
Speaker 1:Linking to what you just said about situation, depending on the situation, but also about the trend against chlorhexidine. We have somebody asking about the usage of chlorhexidine in post-surgery or periodontal treatments. So what would you say about that, about this situation specifically?
Speaker 2:Again, thank you for this question. I think it's very important that when you have an indication like, indeed patient just came through surgery and you need to facilitate wound healing and you see that indeed, mechanical cleaning is, there again, not optimal because you cannot open the mouth due to surgeries, for instance, then indeed chlorhexidine is a very good adjunctive treatment. Just the only thing what patients and clinicians should remember that this treatment should not be too long. Like normally for chlorhexidine, we don't advise usage of longer than two weeks for daily exposure. So again, once there is a medical or dental indication, yes, please apply this to your patients, but keep it short.
Speaker 1:Thank you for this answer, basically saying that antimicrobial usage depends on the clinical situation and we have to make the choice that is best for the patient at the time point he's consulting us. For we have, then, another question, which is broader, on the role of saliva what is the role of saliva in the oral microbiology ecology? What is the role of saliva?
Speaker 2:in the oral microbiology ecology. Well, this is also a very nice question and since I'm really fond of ecology I could go on for hours and I don't think I have that much time Well, I would like to turn it around to make it easier for people to imagine. Can you imagine a patient who doesn't have saliva anymore? Can you imagine what consequences that would have to oral health? And that would hopefully then help you also to envisage what does saliva do with the oral ecosystem, with the oral microbes.
Speaker 2:For instance, when you lose saliva or at least reduce the amount of saliva due to medication or due to disease, then we do see increased carious risk. We do see increased growth of opportunistic pathogens, like candida, for instance. So we have changes in the taste. We have a lot of problems when we lose saliva. Saliva is also important because it's a main nutrient for oral microbes. So saliva determines which microbes grow in a mouse. Saliva contains immune substances, which also prevents certain microbes from growing, or at least from growing too fast, but it also feeds the good microbes. So definitely we need saliva and we need good volume of it and a good composition of it, and bh of saliva again will determine which microbes will stay and which will go.
Speaker 1:So, um yeah, if we lose saliva, we lose oral health, unfortunately so it looks like saliva has interaction, uh, interaction with the, with the bacteria, with the microbiome. And talking about interactions, bacteria do also have interactions between themselves, but also with the environment. One of the next questions we have is about how do bacteria actually interact between themselves and how is the contribution of external factors such as smoking or alcohol?
Speaker 2:Well, thank you for, again, really excellent questions. Well, bacteria, of course, are there in communities. These communities are very diverse and they do interact, and for a very simple reason. Like I just mentioned, saliva functions as a main nutrient for bacteria, but saliva contains very complex, large molecules. Those are called glycoproteins, so proteins for sugar molecules, and they are very complex. And these bacteria? They can break small pieces of these complex molecules away. Each of them is expert in breaking down some small parts, but they cannot break down everything. So what they do? They collaborate. One type of bacteria break down one piece, the other one breaks it again in smaller pieces. So they need each other's help to get energy out of these complex molecules.
Speaker 2:Another way of collaboration is this called food web, that one bacterium produces a substance which is then used by other bacterium so that they use each other's metabolites for feeding the other bacteria. And then there is also a separate, more aggressive interaction. They actually have a war with each other. They can fight competitors for the same food. For instance, streptococci. They produce molecules called bactericins and those can be toxic for other streptococci, so that they are kind of competing out-competing their nephews from the same table.
Speaker 2:You could say they also communicate with each other using small molecules called quorum sensing. So there is a whole flavor of different ways of interacting. So we're always scratching the surface. We actually don't know most of the interactions they have, but we can tell that they're really important. If we didn't have these interactions so both positive ones, we call them synergetic, and negative ones, or antagonistic, like these warfare interactions then some bacteria might take over the whole community and growing out of their proportions, becoming too dominant, and that is what we call oral dysbiosis. You don't want one or two types of bacteria taking over, you want to have a nice, complex, diverse community. So yes, these interactions help to maintain it.
Speaker 1:Before we move to the part of the question on external factors, you mentioned something. May I ask to detail quorum sensing that you mentioned? If you could just detail a little bit this.
Speaker 2:Well, again, that's a very, very broad topic. But quorum sensing you can think of a language. We use words, Bacteria use chemical molecules. So for instance, certain types of bacteria have a molecule which they can produce and other bacteria from the same type can sense this molecule. This kind of translates say oh, I have my brothers very close by, or we are increasing in concentration, meaning we have to go and look for more food.
Speaker 2:They, they talk this way, they use these molecules in understanding about their numbers, how close they are from each other and they can also fight, use this as a fighting molecule, like alerting your neighbors that we have to do something. So it's again a topic which is very exciting, where quite some is known from different biofilms, very little from oral biofilms. So still a lot of research is being done in this field. There are some ideas that these molecules might be also used to remove biofilm, which would be very interesting for oral cavity to interfere with this language of bacteria. So it's again for research, an exciting topic to go into an exciting topic to go into.
Speaker 1:So it's a communication channel and way between bacteria to alert themselves of a problem, of a danger, so that they can actually live in the community.
Speaker 2:Yes, and they can undertake actions. They can express some stress responses. For instance, they can say that, oh, there's antibiotics coming. The upper layer can inform the lower layer, there is something coming and we have to be strong. So yeah, all these antimicrobials induce also this quorum sensing response.
Speaker 1:So a whole world communicating and living by itself, almost, and having its own language, which is very interesting, at least, and for sure, interesting to learn more of. So, coming back to the question of our viewers, there was a path on the contribution of external factors. Now that we know bacteria interacting between themselves a bit more, bacteria interacting between themselves a bit more, how?
Speaker 2:is the part, the role of external factors such as smoking or alcohol. Well, yes, like I think it only makes sense to imagine that any factors which you add on top of this ecosystem, which is normally just shaped by the oral cavity and saliva. But if you add anything, that will always have an effect. And yes, if we take, for example, smoking, I think everybody knows that smoking is not a particularly healthy habit. It has systemic effects. It affects also how our immune system will respond. So we get much less immune response because it has to fight also these negative effects of nicotine.
Speaker 2:So that's the systemic, but also locally things will change because of the presence of tobacco and the products from tobacco and the smoke. So the pH will change, the oxygen concentration will change and that all will involve also changes in the ecosystem, meaning that the different microbes will have less convenient environments to grow and because our immune system is doing some other job and fighting these nicotine effects. So the microbes might grow too fast and again a wrong microbes might grow too fast. And we know from some studies that people who smoke but don't have periodontitis, the studies have shown that they already have a microbiome which resembles microbiome of people with periodontitis, meaning that there is already dysbiosis, and I think that it's because this immune system is really not working properly and not keeping this dysbiotic microbiome to get out of their proportions. So, yes, the effect is really large, and alcohol exactly the same. Alcohol has also systemic and local effects, so you can imagine that it will affect microbiome.
Speaker 1:And I suppose that the dose is important.
Speaker 2:Well, in terms of smoking and alcohol alcohol I think it would be also frequency. If you have, like these, party smokers, going once a week and having a cigarette, probably effect will not be a dramatic. Bacteria are strong, they will recover, but also your body will recover. But you have people who smoke regularly or daily and a lot of cigarettes and definitely the ecosystem cannot handle it and your body and your lungs cannot handle it.
Speaker 1:So yes, everything is dose related. We have a next group of questions about pre and probiotics for you, dr Zahra, and how they work. One of your comments during the conversation was about the oral microbiome and stability. If the oral microbiome is so stable, the question is, how can pro pre and symbiotics work?
Speaker 2:Wouldn't prebiotics be food for good and bad bacteria as well? Thank you, rachel. Again, excellent questions and again there is not a simple answer. The first part if the microbiome is so stable, how all these things can work. Well, they have a very hard time working. They don't work always. It will depend on the situation and it will depend also on the age of the patient. We know that probiotics are easier to get their job done in young children when microbiome is not so stable yet. But indeed, once it's stable, it's much more hard to get them into the mouse. Also because majority of probiotic strains actually are not oral but a gut-derived species. So they don't have tools to attach and to stay in oral cavity. So if there be new probiotics which originate from oral cavity, that would probably make them much more stronger to stay. Then the second part. I think it's also very, very interesting Wouldn't prebiotics be food both for good and bad bacteria? And there we have to look at definition. What do we mean with prebiotics? When we call something prebiotic, that means that those are substances which can be used by bacteria in your mouse and they should have health benefit for the host, for the person. So if they feed bad bacteria. That means already by definition you cannot call them prebiotics. So how do we solve this issue?
Speaker 2:Well, I would use arginine as an example here. Arginine is amino acid. We can get it out from food rich with proteins, like fish and meat. But arginine can also be used as oral prebiotic against the caries risk. So arginine is broken down into ammonia and pH in oral ecosystem is increased. And when you increase pH it actually lowers the caries risk, because these individuals who have caries risk usually have too low pH around their teeth. So that's why we can call arginine a prebiotic against caries.
Speaker 2:But if we take the same arginine and put into the oral cavity of individuals who have periodontal disease, a completely different picture arises. Because in periodontal tissue usually pH is already above 7, so above neutral. These bacteria growing in periodontal pockets actually prefer these conditions when pH is above neutral. They don't like acidic pH, like in the mouse of Keres patient. So these periodontal bacteria also can break down arginine and use it as a food. And what happens? By breaking it down, ph goes up even higher. So it kind of increases the growth of the same periodontal bacteria.
Speaker 2:And then we would definitely not call this a prebiotic, then we would call it a harmful effect of arginine in this particular patient. So the lesson here is not everything fits everyone, so one size of prevention will not fit us all and not everything will be pre or probiotic in the same mouse. So we have to see who is receiving this pre or probiotic and then I can imagine you would like to know what would help these periodontal patients then if they cannot use arginine, right, exactly? That was my next question. Yes, I can guess your question.
Speaker 2:Well then you should think again as ecologists.
Speaker 2:Ah, they don't like low pH, so what can we do to decrease pH locally in this periodontal pocket so that the ecosystem starts to get back to the balance? And then we can help our friends, probiotics and which are usually lactic acid producing bacteria. The name already says lactic acid producing, so they produce lactate and lactate is acid which actually lowers pH in that environment. And when you lower pH these periodontal bacteria will suffer, they will reduce their growth, and other bacteria which are like streptococci, which, like these acidic conditions, will start to grow faster and that will bring back the balance which we want to have. We want to have really nice and diverse ecosystem where both a little bit bad and a little bit good from all kinds of flavors. These bacteria are together and not one group outcompeting others, so there is always, well, something which would help in any situation, but you just have to really think about what kind of patient you have in front of you and what kind of ecosystem approach. You would need Something to lower pH or something to increase the pH.
Speaker 1:And would you have an example, similarly applied in a clinical practice, of a symbiotic that would be harmful in one case but beneficial in another one?
Speaker 2:Well, you mentioned symbiotic, and symbiotic is a combination of the pre and probiotic and to date the one symbiotic I know which is being tested, it's like a strain which can break down arginine. It's being put together with arginine so that you already have the food and the right bacterium and you put it into the mouth. So it's the same story. The result would be raising the pH would be very good and health-promoting in carious risk patients, but probably not so beneficial for periodontal patients.
Speaker 2:But since you are adding the streptococcus which can break down arginine, in this case streptococcus itself might be beneficial for periodontal pocket. So here it becomes a little bit unpredictable because you are adding two things which can have two separate effects. So in this case it's less straightforward to say that maybe patients with periodontal pockets won't benefit. Maybe they do, because then these periodontal bacteria would not eat up the arginine but the streptococcus would, and because the streptococcus would start growing at the same time it also changes the ecosystem. So maybe then it is still beneficial. But I think for that we need to wait for results of clinical studies.
Speaker 1:So thank you, Dr Zahra, for all this information on the pro, pre and symbiotics and the difference of a different type that we need to give to our patients depending on the clinical situation. Again, we have come to the last set of questions, which is about the life stages of patients, Because you mentioned in the conversation again that, as children, the oral microbiome helps to train the immune system. Then what about the oral microbiome as we grow? Does it change from birth to older age?
Speaker 2:Well, thank you again. Really excellent question. Microbiome is something which is evolving. As we get born we don't have microbes yet and they start to evolve. We obtain these microbes from our environment, usually from our parents, and at the same time immune system is also still quite naive. And this combination of growing up and getting microbes and introducing those to our immune system is exactly what immune system needs at that stage. So that's why it's trained to recognize what's good for you and what's not.
Speaker 2:Somewhere around age of three, when we have full dentition, you could say it's our oral microbes have reached quite stable stage. But that's only temporary, because then of course you also start to change dentition from deciduous to permanent and another phase of life starts, which is puberty. So when we go through puberty, due to hormonal effects, all kinds of changes happen, also in the oral cavity. Oral tissue have receptors for sex hormones and these hormones can be used as growth factors for oral bacteria. So we see that usually in teenagers that there is an increase in these periodontal pathogens which like to grow on these hormones. So after that very turbulent stage of life called puberty, a more quiet period approaches and then again you can say oral microbiome is quite stable, except when females get pregnant and again, due to hormonal changes, all kinds of turbulent changes occur also in the oral cavity. So you probably have heard of pregnancy gingivitis. So they can do their best, they can brush their teeth, but they still get swollen gums. That's again because of these receptors of sex hormones in their gums. So the body is overreacting to very low amount of biofilm just because these hormones are there. So your blood vessels are more swollen, opening up and you do get this effect of gingivitis. But again, once that phase is done a quite stable phase if you don't change your lifestyle, don't start smoking or eating too much sugars, the oral microbes will be quite stable.
Speaker 2:But then when you get older, then a new stage appears which we call senescence of tissue or senescence of your immune system. Meaning aging brings all kinds of changes, not only like saliva composition and volume, but also your immune system. Recognition of different microbes will be very different. So your body will start to neglect new microbes coming in and that might introduce some changes into your microbiome because these gatekeepers, these immune cells, are quite tired at older age. So you can imagine that some opportunistic pathogens, maybe staphylococci, coming from skin, might start to work, uh, start to live on on your dentures, on your tongue, but also candida might pop up and start to grow faster than earlier. So all kinds of changes can happen when you get old and your immune system doesn't function.
Speaker 2:Also, when people get ill, get hospitalized, changes can occur because of lack of good oral hygiene. But again, if you're hospitalized, probably there is a condition why you're hospitalized and that again, if you're hospitalized, probably there is a condition why you're hospitalized and that again influences your overall health and that influences your oral health. So you can always get changes and disturbances. If something changes in your life, your microbes will change as well. One thing I forgot imagine that you get braces. It can happen in puberty, but also later. If you get these braces in your oral cavity, again it introduces a big environmental change for the ecosystem. So it will change the microbes. So again, yes, they're stable, but to a limit. If you give them a big enough challenge, they will change.
Speaker 1:So you mentioned the change of the oral microbiome during the auto treatment. What's the role of the oral microbiome in the white spot lesions?
Speaker 2:well, any lesion, white spot or it gets a cavity, is in relationship with the microbes, because they don't. These lesions are a result of microbial action, right? So microbes are consuming these sugars. We are offering them, maybe too often, and that's why we get the lesion and we leave this biofilm on the tooth. So this biofilm is sitting there and the sugars are there, coming, passing by, and microbes get very efficient. Actually, what happens when you offer them sugars?
Speaker 2:Very often, you select for microbes which are very fast in getting energy out of sugars. So those microbes get ecological advantage and they outcompete the others. Also, the microbes which like acidic environment, which can grow in acidic environment, meaning again low pH, those will outcompete the others. So this brings us to the dysbiosis, so that microbes which we don't want to be in big amounts actually start to grow out of proportions. And when they're sitting there and the sugar keeps coming, yes, then they're very fast in making acid and this acid has to go somewhere. So of course then it's neutralized by dissolution of the tooth mineral. So enamel is dissolved by these acids, making again environment neutral so the bacteria can make new acid. So enamel kind of buffers and helps these bacteria. So one thing to deal with it is start brushing and use fluoride toothpaste, so these white spot lesions will be demineralized and won't come back.
Speaker 1:Great. Thank you for this additional insight of the oral microbiome in ortho treatment or microbiome in ortho treatment. And it brings us to the next question from our audience. That is about the kind of support clinicians can bring to patients through this exposure to red microbes during the different phases of life. How can clinicians support that?
Speaker 2:Well, if I would talk to my patients, I would first talk to talk to young parents or people who are wishing to become parents, expecting mothers also fathers really to stress how important is their own oral health, their own oral microbiome, because that's what they are giving away to their child. So when the child is born, it's also very important to share your parental good microbes with your child. It can happen by feeding habits, by licking pacifier or sharing the spoon that you can just give them to help your kids to get your good oral microbes Well and also let your kids play and really don't keep your kid too clean away from all the things, because it needs to get exposure to microbes Well. Of course you also have these pre and probiotic products which you can use if you would like to, especially if you've been on antibiotic treatments.
Speaker 2:I think I'm talking now more about the gut microbes which can suffer from antibiotic treatments. I think I'm talking now more about the gut microbes which can suffer from antibiotic treatments. Then people tend to choose probiotics to improve that. But throughout your life, I think we don't have to worry that we are losing microbes if we are not using aggressive antimicrobials. So getting them is a role of the parent and surroundings. It's very important. And keeping them throughout your life, that's an important part. I think we discussed already in the episode that keeping the microbes, that's the heavy task, not to kill them.
Speaker 1:We have come to the end of our Q&A. Dr Zahra, thank you very much for answering the questions from our audience about the oral microbiome-driven approach to prevent periodontal and peri-implant diseases. I would like to thank you also our audience for your interest in the episode and for the question you submitted to us. We hope we were able to answer to most of them. Make sure you check out the other episodes of our let's Talk Oral Health Expert Series about the prevention of periodontal and peri-implant diseases. Once again, thank you, dr Zahra, for your time and your answer. It was a pleasure to have you back with us.
Speaker 2:Thank you, rachel, pleasure was also mine.
Speaker 1:This was let's Talk. Oral Health by Sunstar. See you all soon.
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