Dr Michael Berthaume,  LSBU’s Deputy Head of Mechnical Engineering and Design, on the genesis of anthroengineering and its potential application to dentistry

What was the spur for beginning work on defining this new academic field?

As an undergraduate at the University of Massachusetts, Amherst, I was interested in both engineering and anthropology. Being in the US, I had the ability to study them both at the same time. But when people asked me what I was going to do with my education, I had no idea as I could find no one else who combined the two fields!

Luckily, I discovered an engineering professor – Professor Ian Grosse – at my university who had a grant with anthropologists to use mechanical models to study human evolution. I began working with him as an undergraduate, ultimately getting my PhD with him.

Over the course of my post-doctoral training, I met many others who combine anthropology and engineering in their work, many in some quite unique ways, and we all had the same story; we were interested in the two fields but, being unable to find others who were, lacked guidance on how we could have a career that combined the two.

We also found it difficult to do research, that is obtain funding and publish our results, as we often weren’t “anthropology enough” for the anthropologists or “engineering enough” for the engineers. As such, we were forced to work twice as hard and never really fit in anywhere. We all wished we had known about each other sooner, so that we could have learned from and with each other instead of having figure out how to combine the two fields successfully all on our own.  So, the biggest inspiration was to give those people an identity – i.e., “I am an anthroengineer” – and provide a space for those people to belong … that is, now, London South Bank University!

Can you describe the process?

That’s a very good question! When I tell people it is my career goal to create the field of anthroengineering, I always follow it up by saying I feel like I am saying I want to be an astronaut! We all know they exist, but very few of us know the process of how to become one.

Over the last five years, I have talked to a lot of people about what this process might entail, and we all agree on a few things. For one, there must be a literature, and that’s what the special issue in the Royal Society Journal¹ has attempted to accomplish; to start the literature of anthroengineering. There also must be a place where people can be educated in the field, and that is what we are starting to do at LSBU. Currently, I am working to create a masters’ course in anthroengineering where people can come and gain training.

There also must be jobs for people to move into after they are trained, and I have started conversations with some companies about what this might look like. Finally, there needs to be a division, department, or school dedicated to it; a Division of Anthroengineering, if you will. I’m working on that.

Why did you choose to include dentistry as an area in which anthroengineering could be applied?

Interestingly, I have been studying dental biomechanics since I began research back in 2009. My very first project was to investigate the relationship between tooth shape and biomechanical function in a few species of extinct hominins. That led to my dissertation, and several studies since then where I have been continuing this line of work, investigating the relationship between complex tooth shapes – like molars – and function. 

Announcing the new field, you said: “Current dental models fail to relate tooth shape and how food breaks down during chewing.” Can you explain?

It’s what I’ve been looking at for the last 12 years! People often make sweeping statements like “sharper teeth require less force or energy to break down foods.” This is certainly true for simple teeth, like canines or incisors, where there is only one cusp or one blade interacting with the food item per tooth.

But in molars, there are many cusps contacting the food item per tooth at the same time. This means the forces and energy being transferred from the tooth to the food item are not being transferred at a single point or along a single line, but over a set of points. When this multi-cusp-tooth-food interaction occurs, those fundamental principles begin to break down. 

And you added: “This means that dentures and implants do not function as well as they could.”

I have not carried out research into this area myself, but quite a few studies have shown that, the fewer teeth you have, the lower your quality of life². Similarly, the biomechanical point of mastication is to break food into smaller pieces. This creates a higher surface-area-to-volume ratio for the food particles, which gives the bacteria in the gut more surface area to act on.

As a result, more nutrients and calories are extracted from smaller food particles – although, there is a threshold under which all particles are “small enough” to be fully digested, and some foods, like jelly, will naturally break down in the stomach. In general, this rule of thumb is more applicable to unprocessed, “natural” foods like salads, whole fruits, and steak.

In what ways do you think an analysis of how teeth have evolved in humans might lead to new discoveries?

In many mammals, there is a close relationship between tooth shape, size, and function. For example, the molars of horses are covered in these sharp ridges which do an excellent job of cutting hay, and lions have these sharp, blade-like carnassial molars which are really good at cutting muscle and tendons.

Our molars, for example, are much smaller than you would expect for a mammal of our size. They also have extremely thick enamel which has woven prisms – presumably these are adaptations for resisting a bite force that is relatively high given the size of our molars.

By having a better understanding of what selective and non-selective evolutionary forces have shaped our teeth, we can get a better understanding of what they were “designed” to do and what we must do to better maintain them now.

For example, our thick enamel and soft, compliant diets mean we wear our teeth much slower nowadays compared to our ancestors. Some have hypothesized having high crowned cusps is the reason abfractions are so common nowadays, and we actually need to be wearing our teeth quicker.

We could also redesign denture crowns so, instead of looking like the teeth they are replacing, they are shaped like a horse’s, for example, so they are better at cutting relatively flat food. Could you imagine sitting down to a meal and popping in a pair of dentures with human incisors but lion-like carnassial molars to help you cut your steak!

How do you see anthroengineering being applied to dentistry?

There are a few dental projects I would love to see get off the ground. One would be to apply what we know about tooth shape and food item breakdown towards the redesign of denture and dental crowns so that people can continue to eat the foods they like, as they lose their teeth.

Another would be to take what we know about the relationship between enamel microstructure and how teeth wear and applying that to false teeth so that they wear in a manner which maintains dental function.

Finally, I think we can translate a lot of what we know about tooth roots and their variation in size and shape, and how they are connected to the bone to improve the ways which we anchor implants to our jaws.

Of course, my list is tailored towards teeth – given my research – but there is also a lot we can use from anthroengineering to take what we know about how primates chew, for example, to improve masticatory kinematics – jaw movements – and kinetics – muscle activation patterns.

Have dental professionals had an input into your work?

I have talked with a few and we agree there is lots of potential for future work, but unfortunately have not collaborated yet. Mostly, the dental work I have done in the past has been with other anthropologists, biologists, and engineers but I would love to work with dental professionals in a research context. Please get in touch! You can email me on: berthaume@lsbu.ac.uk

¹https://royalsocietypublishing.org/toc/rsfs/2021/11/5

²https://journals.sagepub.com/doi/full/10.1177/0022034516657992