Tag Archives: Chewing

Chewing robot developed to test gum as a potential drug delivery system

Researchers at the University of Bristol (UoB) have created a robot for a peculiar purpose: chewing gum.

Image via Pixabay.

Robots keep coming for our jobs. Today, they’ve taken one of the easier ones — gum chewer. However, rest assured, it’s all in the name of science.

The robot is dentated to become a new gold standard for the testing of drug release from chewing gum. It has built-in humanoid jaws which closely replicate our chewing motions, and releases artificial saliva to allow researchers to estimate the transfer of substances from the gum to a potential user.

I have a mouth and I must chew

“Bioengineering has been used to create an artificial oral environment that closely mimics that found in humans,” says Dr Kazem Alemzadeh, Senior Lecturer in the UoB Department of Mechanical Engineering, who led the study.

“Our research has shown the chewing robot gives pharmaceutical companies the opportunity to investigate medicated chewing gum, with reduced patient exposure and lower costs using this new method.”

Chewing gum is recognized as a possible drug delivery method, but there currently aren’t any reliable ways of testing how much of a particular compound they can release during use.

The team’s theoretical work showed that a robot could be useful for this role — so they set out to build it and test it out.

The team explains that the robot can “closely replicate” the human chewing process. Its jaws are fully enclosed, allowing for the amount of released xylitol (a type of sweetener common in gum) to be measured.

n) shows the final prototype, l) shows a digital model of the robot.
Image credits Kazem Alemzadeh et al., (2020), IEE Transactions on Biomedical Engineering.

In order to assess the robot, the team had human participants chew the gum and then measured the amount of xylitol it contained after different chewing times. The team also took saliva and artificial saliva samples after 5, 10, 15, and 20 minutes of continuous chewing. The robot’s gum was then tested similarly and compared to that of the human participants.

The release rates between these two chewed gums were pretty similar, the team found. The greatest release of xylitol occurred during the first five minutes. After 20 minutes of chewing, only a low level of this compound remained in the gum, regardless of how it was chewed.

All in all, this suggests that the robot is a reliable estimation tool for chewing gum. It uses the same motions and chewing patterns as humans, and its artificial saliva seems to interact with the gum in a very similar way. As such, it could serve as the cornerstone of medical chewing gum.

“The most convenient drug administration route to patients is through oral delivery methods,” says Nicola West, Professor in Restorative Dentistry in the Bristol Dental School and co-author of the study.

“This research, utilizing a novel humanoid artificial oral environment, has the potential to revolutionize investigation into oral drug release and delivery.”

The paper “Development of a Chewing Robot with Built-in Humanoid Jaws to Simulate Mastication to Quantify Robotic Agents Release from Chewing Gums Compared to Human Participants” has been published in the journal IEEE Transactions on Biomedical Engineering.

P. robustus skull.

One of our extinct ancient relatives developed a chewing pattern unique among primates

Not all human ancestors chewed the same way, new research reveals.

P. robustus skull.

Paranthropus robustus fossil from South Africa SK 46 (discovered 1936, estimated age 1.9-1.5 million years) and the virtually reconstructed first upper molar used in the analyses.
Image credits Kornelius Kupczik / Max Planck Institute for Evolutionary Anthropology.

While we’re the only one that made it up to the present, we’re by no means the only species of hominins — the evolutionary group that includes modern humans and now-extinct bipedal relatives — that popped up throughout history. At least one of our human ancestors, new research shows, developed a unique way to chew.

Ancient chow

Being able to properly chew your food is a matter of life and death. It helps break food down into tiny pieces so they can be swallowed and digested. But every species has its own way of going about it — based on their diet and individual morphology.

You can learn a lot about an animal by looking at what it eats and the way it chews on it, and that stands true for humans as well as wildlife. Palaeoanthropologists go to great lengths to reconstruct the diets of ancient hominid species, as diet underpins our evolutionary history. A high-quality diet, for example, coupled with meat-eating, provided the nutrients that modern humans needed to develop our big brains. Some of our hominin relatives, by contrast, likely went extinct because of their diets (for example, the Neanderthals).

Two extinct hominin lineages — Australopithecus africanus and Paranthropus robustus — have constantly sparked debate in regards to their diet since their discovery. An international team of researchers, led by members from the Max Planck Institute for Evolutionary Anthropology, studied the splay and orientation of their fossil tooth roots in an attempt to settle the debate once and for all. Their findings surprisingly reveal that P. robustus employed a unique way of chewing food — one that hasn’t been seen in any other hominin species to date.

The team used high-resolution computed tomography and shape analysis to determine how teeth roots were oriented within the jaw of ancient hominin lineages. Based on this information, they then gauged the direction of the load during mastication — i.e. the direction force was applied while they chewed.

By comparing the virtual reconstructions of 30 hominin first molars from lineages in South and East Africa, the team found that Australopithecus africanus had much more widely-splayed roots than either Paranthropus robustus or the East African hominin Paranthropus boisei. This yielded a surprising revelation about P. robustus.

“This is indicative of increased laterally-directed chewing loads in Australopithecus africanus, while the two Paranthropus species experienced rather vertical loads,” says Kornelius Kupczik of the Max Planck Institute for Evolutionary Anthropology, first author of the paper.

Unlike all other hominins involved in the study, P. robustus showed a ‘twist’ in the roots of their teeth — suggesting a slight rotational and back-and-forth movement while chewing, the team explains. Other characteristics of their skulls support this observation, they add: the structure of the enamel also points towards a complex, multi-directional motion. Microwear patterns in the enamel (which the team reports are “unique among primates”) also point to a different motion of the jaw while masticating compared to how we do it, for example.

While diet also has a major part to play in shaping our and P. robustus‘ skulls, as well as in the patters of wear observable on their teeth, the team says dietary differences alone cannot account for all that they’re seeing.

“Perhaps palaeoanthropologists have not always been asking the right questions of the fossil record: rather than focusing on what our extinct cousins ate, we should equally pay attention to how they masticated their foods,” concludes co-author Gabriele Macho of the University of Oxford.

The research could have implications beyond paleoanthropology, the team explains. By studying the particularities of P. robustus‘ morphology, its mastication patterns, and its effect on the lineage’s teeth, “we can eventually apply such findings to the modern human dentition to better understand pathologies such as malocclusions,” explains co-author Viviana Toro-Ibacache.

The paper “On the relationship between maxillary molar root shape and jaw kinematics in Australopithecus africanus and Paranthropus robustus” has been published in the journal Royal Society Open Science.

We owe the shape of our jaws, at least in part, to our ancestors’ love of cheese

The advent of farming, with its ‘softer’ foods compared to previous hunter-gatherer menus, had a subtle but noticeable effect on the shape of human skulls, anthropologists from the University of California, Davis report.

Skull jaw.

Image credits Eliane Meyer.

Wild foods generally tend to be rougher than the stuff we’re used to nowadays. In other words, our hunter-forager ancestors had to put a lot more effort into chewing dinner than we do — they had to chew more and more often before dinner got in their bellies. Previous research has shown that there is a connection between skull shape and the advent of agriculture, but they haven’t gone as far as quantifying exactly how these changes developed over time.

So a team from UC Davis, made up of postdoc David Katz, statistician Mark Grote and associate anthropology professor Tim Weaver looked at 559 skulls and 534 lower jaws from over two dozen pre-industrial populations to see exactly how diet altered the shape and size of human skull bones as we transitioned to agriculture.

“The main differences between forager and farmer skulls are where we would expect to find them, and change in ways we might expect them to, if chewing demands decreased in farming groups,” said Katz, who is now a postdoctoral researcher at the University of Calgary, Alberta.

Overall, the team found subtle but noticeable changes in the skulls of communities that grew and consumed dairy, cereals, or both. The greatest effects were associated with groups whose diets included a large percentage of dairy and dairy products, which suggests a direct link between the softness of the food and morphological changes.

However, diet wasn’t the most important factor dictating skull characteristics. For example, the team reports that morphological differences between males and females, or those between individuals eating the same diet but came from different populations had a more pronounced effect.

It’s interesting to see how our lifestyles play a direct role in our evolutionary path. The effects are less pronounced than “neutral evolutionary processes” such as genetic drift, mutation, and gene flow structured by population history and migrations. But even diet’s more muted contribution to the Homo sapiens we all know and love today shows that we’ve been meddling with our evolution for a long time now — whether we want to or not.

With the advent of genetic engineering, we’re bound to have an even more pronounced influence in the future. Time will only tell what that influence will be.

The paper “Changes in human skull morphology across the agricultural transition are consistent with softer diets in preindustrial farming groups” has been published in the journal Proceedings of the National Academy of Sciences.

chewing highland beauty

Despite oral hygiene, chewing still leaves nanowear on teeth

Oral hygiene is important for teeth and gum health but despite our best efforts, the enamel still suffers wear and tear. A new study found that no matter a person’s diet, the act of chewing food wears teeth down at the nanoscale.

chewing highland beauty

A chewing highland beauty. Credit: Pixabay.

Peter Ungar, an anthropologist, and Ryan Tian, associate professor of inorganic chemistry, both at the University of Arkansas, worked with Chinese colleagues at the Southwest Jiaotong University in Chengdu to study the different kinds of wear on the nanostructures that make up tooth enamel.

Enamel is the outer layer of each tooth and is the hardest, most highly mineralized substance in the human body. It’s made of ribbon-like strings of nanoparticles called hydroxyapatite crystallites, which are stacked on top of each other and glued together by proteins. Enamel is actually translucent, so you can see right through it. Dentin, the bulk material of any tooth, is what’s responsible for tooth color — whether white, grey, or yellowed.

Using high power microscopes, researchers imaged the surface of human molars as they applied pressure using tips made of different kinds of materials. This simulated the pressure created on enamel when crushing food. They also moved the tip across the surface of the molars, simulating the action of teeth moving against each other when eating.

Researchers found that scratching damaged molars more than indentation. In other words, blunt force was less damaging than sharp objects scraping against teeth, i.e. chewing. There was visible damage in both cases, nevertheless.

Three kinds of defects on the surface of enamel were reported — plucking, deformation, and fragmentation.

Nanoscale crystallites that make up tooth enamel before and after researchers applied pressure. Credit: University of Arkansas.

Nanoscale crystallites that make up tooth enamel before and after researchers applied pressure. Credit: University of Arkansas.

Plucking happened when the crystallites were separated from each other. When the force was increased, deformation occurred which represents the bending and squeezing of crystallites. Applying even more pressure caused the chemical bonds holding the crystallites together to break, resulting in fragmentation.

“Hydroxyapatite crystallites are the fundamental units of enamel, each less than 1/1000th the thickness of a human hair,” said Ungar. “Most research on tooth wear to date has focused on effects at much larger scales, but we have to study enamel at this finer level to truly understand the nature of how the hardest tissue in our bodies resists wear and tear.”

Understanding how chewing damages teeth at a fundamental level is important not only for clinical dentistry but also for seemingly unrelated fields like evolutionary biology. This basic understanding could help some scientists spot new clues from archaeological remains.

“The findings in the surface tribological chemistry can help us understand the nature of the interfacial chemical bonding between the nanoparticles that Mother Nature uses to make biominerals of all types on demand,” said Tian.

Scientific reference: Enamel crystallite strength and wear: Nanoscale responses of teeth to chewing loadsJournal of the Royal Society Interface (2017).

cow chewing

‘Chewing like a cow’ helped early mammals thrive in the wake of dinosaur extinction

We’re generally more interested in what’s on our plate than how we eat it, but here’s an interesting thought you can bring to the dinner table tonight. According to evolutionary biologists from the University of Chicago, the same side-to-side chewing motion that’s familiar across most mammals helped our early ancestors grind food with their molars and opened up access to a more diversified diet. This evolutionary edge may have gone a long way 66 million years ago, during the mass extinction event of the Cretaceous known for wiping out the dinosaurs.

cow chewing

Credit: Pixabay

You’ll often hear aviation engineers use the terms ‘pitch’ and ‘yaw’ to describe the movements of airplanes, where pitch rotation results in basic up and down movement while yaw rotation results in side-to-side, crosswise motion. The same terms are employed by the biologists as well, when talking about the mechanics of motion of various body parts. For instance, almost all modern mammals from deer to kangaroos to humans share similarities in their jaw and muscle structure that enable both pitch and yaw.

David Grossnickle, a graduate student at University of Chicago’s Committee on Evolutionary Biology, wanted to investigate how mammalian chewing evolved. He painstakingly combed through 2D photos of early mammal fossils and 3D data collected from modern mammal specimens by the Field Museum, and eventually spotted some patterns.

The analysis revealed mammal teeth, then their muscles, were increasingly adapting to allow yaw chewing. For instance, species began to develop projections on the upper molars that fit into the basin on the lower counterpart. The development caused changes in the musculature of the jaw which had to adapt to provide more torque required for side-to-side movements. Another important morphological change was around the ears, as a bony attachment between the middle ear elements and jaw became gradually lost.

Eventually, early mammals became able to grind food between the molars like a mortar and pestle instead of cutting it with simple up and down movements like a knife. The whole process can be traced back to as early as 160 million years ago.

“If you have a very specialized diet you’re more likely to perish during a mass extinction because you’re only eating one thing,” Grossnickle said in a statement. “But if you can eat just about anything and 90 percent of your food goes away, you can still live on scraps.”

Credit: Nature.

This adaptation in the jaws and teeth may have been key to the success of early mammals following the great dinosaur extinction. Like dinosaurs, mammals were hit hard by the nuclear-winter-like conditions left in the wake of the giant asteroid impact which hit Chicxulub, Mexico, but due to a combination of factors like small size and high breeding rates, the mammals were able to rebound. Diet and, equally important, chewing motion seem to have played a very important role as well.

“The continued presence of tribosphenic molars in many modern mammalian lineages provides strong evidence of its evolutionary importance. Thus, the concurrent evolutionary changes to jaws, molars, ears, and chewing cycles in early cladotherians may have been an especially significant event in mammalian evolution,” Grossnickle concludes in his paper.

Journal reference: David M. Grossnickle. The evolutionary origin of jaw yaw in mammals. Scientific Reports, 2017; 7: 45094 DOI: 10.1038/srep45094

The Crunch Effect — how listening to your chewing can help you lose weight

The sounds you make while chewing have a significant effect on the amount of food you eat, a new study has found. The results suggest that people are likely to consume less if they can hear themselves eating.

Image via tclw.das.ohio.gov

Researchers at Brigham Young University and Colorado State University have found that your TV, radio, and computer are making you fat. Not by bombarding you with food ads (though they totally are) but by blocking the sounds of your chewing. In a recent study, they found that the noise your food makes while you’re eating can have a significant effect on how much food you eat.

“Sound is typically labeled as the forgotten food sense,” adds Ryan Elder, assistant professor of marketing at BYU’s Marriott School of Management. “But if people are more focused on the sound the food makes, it could reduce consumption.”

“For the most part, consumers and researchers have overlooked food sound as an important sensory cue in the eating experience,” said study coauthor Gina Mohr, an assistant professor of marketing at CSU.

The team carried out three separate experiments to quantify the effects of “food sound salience” on quantity of food consumed during a meal. In one experiment, participants were given snacks to eat while they wore headphones playing either loud or quiet noises. The ones loud enough to mask the sound of chewing made subjects eat more — 4 pretzels compared to 2.75 pretzels for the “quiet” group.

In another of their experiments they found that just having people hear chewing sounds through an advertisement can decrease the amount they eat.

Elder and Morh call this the “Crunch Effect.” The main takeaway of their work should be the idea of mindfulness, they said. Being more mindful of not just the taste and physical appearance of food, but also of the sound it makes can help consumers to eat less.

“When you mask the sound of consumption, like when you watch TV while eating, you take away one of those senses and it may cause you to eat more than you would normally,” Elder said.

“The effects many not seem huge —one less pretzel— but over the course of a week, month, or year, it could really add up.”

So the next time you sit down for a meal, take your headphones off and mute the TV. Or find a movie where there’s a lot of very audible chewing.

The full paper, titled “” has been published online in the journal Food Quality and Preference and is available here.