In the Proceedings of the National Academy of Sciences, researchers show that children from lower-income backgrounds and those who go through greater adverse childhood experiences get their first permanent molars earlier. The findings, generated initially from a small study and replicated using a nationally representative dataset, align with a broader pattern of accelerated development often seen under conditions of early-life stress.

"It's really important for us to understand how to detect early maturation sooner," the senior author says. "Right now, we're relying on seeing when kids hit puberty, which might be too late for some meaningful interventions. If we can inexpensively see that a child is experiencing this maturation earlier, we might be able to direct more intervention resources toward them."

Broadly speaking, the lab studies how the brain changes and grows as people learn. It's well-established that stress during childhood speeds up maturation and that children who hit puberty earlier are at greater risk for both physical and mental health problems in adulthood.

Beyond that, in studies across primate species, molar eruption has been used to measure childhood length and correlates with a number of other developmental events. Similarly, for humans, the timing of dental events often plays a role in estimating biological age.

"That all made molar eruption a compelling developmental indicator," says another author.

It helped that more than 100 children, ages 4 to 7, had been participating in two Penn brain development studies, which included structural and functional MRI scans. "There's one type of MRI scan called a T2 weighted scan where you can visualize the morphology of the tooth pretty well," the author says. These scans—typically used to look at the brain—showed the researchers just how close these molars were to breaking through the gum line.

"The scale ranges from 1 to 4," the author says. "At the low end of the scale is 1, which is before the tooth has really developed at all. As the tooth emerges, there are intermediate stages, and the highest rating, a 4, is when the tooth is fully in the mouth and parallel with the other teeth." Four molars each received a score, which then got averaged, leaving a single score per individual.

Controlling for factors like age and gender, the researchers then looked for associations between early environment and molar eruption. "What we found is that income and adverse childhood experiences are both individually associated with molar eruptions status," the author says.

Those findings derived from just 117 participants, so although the correlation was clear, the authors hoped to replicate what they'd seen.

Though some facets differed—NHANES measures dental development a little differently, for example—the models showed similar results, indicating a connection between lower family income and earlier first molars.

https://penntoday.upenn.edu/news/Penn-researchers-link-childhood-stress-early-molars

https://www.pnas.org/content/118/24/e2105304118

http://sciencemission.com/site/index.php?page=news&type=view&id=publications%2Fearly-life-stress-is&filter=22