Tooth decay affects nearly everyone at some point in their lives. Indeed, half of those reading this article are likely to have it right now. It’s common knowledge that a sugary diet can lead to cavities, but specific bacteria in our mouths also play a role. As a result of eating sugary foods, they produce acids in their mouths. When this happens frequently, the mineral concentration of the tissue that makes up a tooth, including enamel and dentine, decreases. This is known as demineralisation, and it eventually leads to cavities.
Tooth decay is a common and unfortunate problem for many of us, but two studies from the University of Otago show that it is also a problem for other primates, as well as our fossil relatives and ancestors.
Cavities, according to Dr. Ian Towle, a former Sir Thomas Sidey Postdoctoral Fellow in Otago’s Faculty of Dentistry, are often thought to be a modern disease unique to humans, caused by a diet high in processed sugary foods. However, he claims that there is growing evidence that tooth decay occurs to some extent in other animal groups.
Our new research shows that caries occurs in wild primates in low frequencies, though this varies greatly between groups and the teeth affected, This research helps us understand changes in diet and behavior during human evolution, as well as specific behaviors in our living primate relatives.Dr. Ian Towle
“Our new research shows that caries occurs in wild primates in low frequencies, though this varies greatly between groups and the teeth affected,” he says. “This research helps us understand changes in diet and behavior during human evolution, as well as specific behaviors in our living primate relatives.”
Dr. Towle and colleagues examined over 8000 extant primate and fossil human teeth to assess variation in tooth decay patterns in relation to diet and behavior for the study, which was published in the American Journal of Primatology and the South African Journal of Science.
They discovered that 3.3% of teeth in living primates had caries, which is comparable to the incidence in fossil humans (ranging from 1 to 4 per cent of teeth in different species). All caries in the fossil human samples studied, on the other hand, were on the back teeth, whereas the vast majority in living primates were on the front teeth.
“The fascinating feeding habits of animals such as chimps, which use their large front teeth to help suck sugary liquid out of figs, contribute to the development of caries patterns rarely seen in humans. Indeed, in humans, our back teeth are the most affected by dental decay, whereas in other primates, the front teeth are typically affected” According to Dr. Towle.
Another intriguing aspect of this study was that female chimps had more caries than males (9.3 percent vs. 1.8 percent), a sex difference that is frequently observed in humans. The study also revealed how similar decay patterns are between captive primates and humans, emphasizing how primates frequently do not engage in specific natural behaviors in captivity.
“Caries has occurred throughout human evolution and does not appear to have changed much over millions of years, with less than 5% of teeth affected. However, with the advent of agriculture, this rapidly increased to more than 20% of teeth having cavities in some samples.”
This research is part of a larger body of work by Dr. Towle and colleagues on the teeth of primates and human ancestors, which has been mentored by Dr Carolina Loch of Otago’s Faculty of Dentistry.
“I hope that this aspect of the research will help the general public understand how living primates have complex and varied feeding behaviors while sharing this common disease with us. Tooth decay has the potential to provide unique ecological insight into extinct primate groups, according to researchers” According to Dr. Towle.
Cavities have been observed in primates in particular, as well as in a wide range of prehistoric species. However, dental decay is still considered rare in wild primates living today, and experts disagree on whether deep cavities found within the front of their teeth are actually tooth decay caused by cavity-forming bacteria, or holes caused by factors other than tooth decay, such as enamel weakness.
In a recent study, we wanted to know for sure whether primates get tooth cavities and where they are found in the mouth. We examined 8,000 teeth from 11 different primate species using a 3D imaging technique known as micro-CT scans.