Mass. General Hospital scientist, Erin Dunn, ScD talks about a new way to tell children’s mental health development through baby teeth.
Interview conducted by Ivanhoe Broadcast News in 2022.
What do you study in your lab?
DUNN: I’m an epidemiologist, and epidemiologists are data doctors. We are trained to be able to identify different risk factors that shape health and well-being over the course of the lifespan. And my research group based at Mass General Hospital studies risk for depression. And so we’re trying to identify new tools that we can use to characterize people who might be at greater risk for experiencing depression at some point in their life, and then to be able to use those insights to help identify new areas for intervention so that we can prevent depression as early on in the lifespan as we possibly can, or delay its first onset.
You and your colleagues were looking at baby teeth. How have you framed the study, who you asked for participation, and what you’re looking at?
DUNN: We study baby teeth, which is a really unusual marker, I think, for a lot of people. Baby teeth are something that my research group has started studying over the last couple of years because we think they are fossilized records of people’s early life experiences. So baby teeth are really absolutely fascinating. They start forming during prenatal life, and then they continue forming over the first couple of years of life. And what’s really amazing about baby teeth is that the way that they form over development is very similar to the way that trees develop, and that if you take a cross-section of a true, of a- if you take a cross-section, let me restate- restart that.
It’s very much like a tree, right?
DUNN: Yeah. So, baby teeth are very similar to trees, so similar to the way that trees develop in terms of leaving behind these incremental records of their growth. Our teeth do the same thing. So if you were to take a cross-section of a tree, you’d notice those incremental growth lines that correspond to how old the tree was. You see similar lines in our baby teeth. And just as you would see in a tree, lines that are sometimes darker or wider, you can see differences in those characteristics within baby teeth. And we think that those differences in terms of the width of the lines.
What are some of the things that you can tell from looking at the differences in the lines on the teeth?
DUNN: When we study teeth, we’re looking at differences in the width of these growth lines, we’re also looking for differences in how dark or light they are, and we’re trying to correlate that with differences in people’s experiences of early life stress. So we’re trying to see if we can see evidence essentially recorded in baby teeth in terms of these incremental growth marks that might be indicators of early life experiences. And then we also do other things to look at teeth. So we’re not just interested in those incremental growth patterns, but we also study how thick the enamel is, that outermost white part of our teeth, we also look at the color of the tooth and other things. And that way we think that teeth might be these really interesting records that can record, at multiple different scales, information about our early life experiences.
Can you talk a little bit about the study that you had ongoing about prenatal stress?
DUNN: One of the biggest studies that we’ve been doing in my group is a study called STRONG, which stands for the stories teeth record of newborn growth. So we just finished recruitment for that study. We recruited participants who were pregnant or raising a newborn during the timing of the Boston Marathon bombing, which was this massive stressor that affected the Boston community. So what we’re doing now with that study is to try to be able to correlate mom’s reports of how stressed she was as a result of the bombing with what we’re seeing showing up in her children’s teeth.
How are you getting the teeth? Is it a call for people of a certain ages, their children are losing their baby teeth?
DUNN: So we’re getting the teeth from kids in our STRONG study through- let me back up. We’re getting the teeth from kids in our STRONG study because we send them tooth kits. So in our tooth kit, it includes a series of tubes that moms can use to send back their children’s teeth to us and to preserve them so that they don’t get damaged. And that’s the main way that we’ve been able to recruit or been able to identify people’s teeth for the study.
How many teeth have you collected thus far? Do you have numbers of teeth coming in or out?
DUNN: We’ve collected an amazing number of teeth from an amazing number of moms in the study. So we’ve recruited over 200 mom-child pairs for the study, and we have over 700 different teeth that we’ve been able to collect. So folks within my group have been working really hard to try to characterize those teeth so that we can learn from them.
Once you get the teeth, how do you go about processing them so you can look and see what kind of information you might gain from them?
DUNN: So when we get teeth into the group, there’s a number of different things that we do with them. So after we unbox them, the first thing that we do is just look at them and we try to figure out what type of tooth it is? Is it an incisor? Is it a canine? Is it a molar? And that helps us to be able to understand what period of development we might be able to capture from that tooth because every tooth develops on its own timescale. So in that way, we think about every tooth as having the potential to tell its own story about a period in development. So then we start to look more in-depth at the teeth. So we look at the color of the tooth and other characteristics that we can see on the outside of the tooth. We take high-resolution images of the tooth. And then we start to get a little bit more granular. So we use micro CT imaging to try to characterize different components of the tooth. So for example, how thick the enamel is, that’s the white outermost part of the teeth or other characteristics of those tissues. And then we start to get even more in-depth with teeth and where we cut them in half and look at the presence of those incremental growth marks or those tree ring-like structures within teeth.
I know that you’re still recruiting at this point, so you still have teeth coming in or are you done with the group?
DUNN: So we’re done with recruiting and getting new moms into the study, but those moms still have children who are losing teeth and we are loving all of them that come in. But we are actually in the process of starting to launch some new studies where we’re hoping other moms will come forward and other families might be interested in sharing some teeth with us.
Do you have any early indications from the teeth that you’ve studied, what you might be able to find? Are you finding a link between the stress and the state of what you’re finding on the teeth?
DUNN: We are starting to see some interesting evidence from the teeth that we’ve been able to analyze so far, that stress might actually be recorded in teeth. So we have two studies that we’ve published on so far. One where we’ve been able to correlate mom’s exposure to experiences of depression and anxiety, and how that correlates with a particular growth line in teeth called the neonatal line, that differentiates the time period of our birth. I can restate that part again.
Are you looking at the neonatal line?
DUNN: So we were in that study looking at the neonatal line and we were able to correlate levels of exposure to maternal depression and social support with the width of that neonatal line, which is a line that’s incredibly cool because it differentiates our prenatal life from our postnatal life. So it’s essentially a marker in teeth that allows you to be able to characterize, differentiate the process of our birth.
What’s the importance of being able to have those early markers and know that stress may be making an impact? When you have that knowledge, then what’s the next step?
DUNN: Being able to identify kids who’ve experienced early life stress is critical. And the reason for that is because we know that these early life stressors are really predictive of future health, not just in childhood in adolescence, but even throughout adulthood. And so if we can be able to better identify kids early who’ve experienced these early life stressors, we can then more quickly connect them to interventions that might be able to help reduce their risk of experiencing adverse health outcomes across their lifespan. And the promise of teeth is that we can potentially have this biomarker, this tool that falls out of our mouths naturally. It’s the only part of our body that falls out in a healthy way. And that we might be able to use the data that we can extract from teeth and not rely on just self-report information alone to help identify kids who might need some extra help in the future.
Is there any study about molars or teeth that fall out at an older age? Can this be studied as well and can you glean information from those two?
DUNN: No, I think there’s potential to be able to learn from every possible tooth, both baby teeth and permanent teeth. So every tooth develops on its own timetable, and that means that there’s potential for every tooth to tell its own story about a period in development. So from baby teeth, you can really learn a lot about early life experiences in early life and what was going on in the earliest periods of development. But as you start to get some of the later forming teeth like the molars, you might be able to piece together other periods of development. And in that way, I think it’s also really compelling that you’ve got different opportunities to study teeth across the first two decades of life. So you have the first opportunity when kids naturally lose their teeth around age six. So maybe instead of sending those to landfills and throwing them out or having them stored in a drawer, and maybe those could one day be used to help guide prevention opportunities. And I think orthodontics and the time period in adolescents is also another time period where instead of those teeth that can sometimes be extracted to make room for orthodonture, those could also be studied. And the same goes for wisdom tooth surgery. Wisdom tooth surgery often happens when kids are in that transition to early adulthood and they’re leaving home for often the first time, major uptick in risk for psychiatric disorders. You often see things like schizophrenia and bipolar disorder emerge for the first time during those periods in development. So imagine if you could use these tools to be able to help guide prevention opportunities.
You refer to the project and you call yourself the science tooth fairy?
DUNN: That’s right. I am the science tooth fairy.
Can you explain just that phrase? How do you describe it?
DUNN: Yeah, I’m the science tooth fairy. I am a scientist who collects and studies teeth.
Is there anything I didn’t ask you that you would want people to know about your research?
DUNN: I think one thing that’s helpful for people to know about this work is just how interdisciplinary it is. And I think I’m really proud of the fact that we have so many different people that are working from different disciplines that are part of this work. I’m an epidemiologist by background, but we’re working with folks who are in pediatric dentistry and biological anthropology and archaeology, and in other areas. And I think we have the potential to make some really interesting discoveries when people from different fields come together.
END OF INTERVIEW
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