Author: admin

Teeth on display at the Wellcome Collection, London. — Image by © Tim Sandle.

Sensory neurons inside the tooth send pain signals to the brain, as is well-established. A new study reveals greater functionality; here, these neurons are multitaskers that also trigger a jaw-opening reflex that almost instantaneously prevents damage and further injury to teeth.

The reflex that pops open the lower jaw was a widely known craniofacial reflex, but until this study was published the cellular origins of this phenomenon were not known.

With the study, University of Michigan researchers in sensory neuroscience, dentistry and mechanical engineering found the origin using special live imaging, behaviour-tracking tools and mice molars to uncover the neurons’ additional role of monitoring the inner tooth and outer enamel.

The discovery and understanding of this additional role shows how important healthy, active nerves are for preserving teeth.

“We suspected there was a more fundamental role for tooth nerves,” says Joshua Emrick, senior author of the study and assistant professor at the U-M School of Dentistry in a research note. “When we consider regenerating a tooth pulp, we need to bring back the nerves.”

The science team looked at how nerve cells reacted to stimulation of the molar teeth of mice in real time. These experiments have revealed a newly defined, protective role for intradental High-Threshhold Mechanoreceptors (HTMR), which are highly specialized sensory neurons that respond to tooth damage. These HTMRs detect dangerous threats and send the message rapidly to the brain for instantaneous action.

“Our study challenges the prior assumption that nerves inside the tooth primarily function to elicit pain and force us straight to the dentist for help,” Emrick adds. “If you’ve ever accidentally bitten down on your fork, you’ve probably experienced a startling jolt, but also stopped short of fracturing your teeth. You may thank these intradental HTMRs for that.”

The reflex is really about self-preservation

Continuing with the importance of the finding, Emrick continues: “We think protection of the teeth through this jaw-opening reflex is highly conserved among mammals that haven’t developed the ability to replace teeth—like humans or in the molar teeth of mice…Our work reports an ability to use these neurons to also elicit pain which will open up possibilities for developing new methods for relieving toothache at the dentist’s office.”

To break it down further, the study, shows that when enamel or dentin is damaged, the neurons fire a response. Follow-up experiments determined what happened after the HTMRs were activated. As previously known, the research group identified that they trigger acute pain, yet surprisingly they also witnessed a rapid jaw-opening reflex within 5 to 15 milliseconds of the activation.

HTMRs may also protect other oral and body structures from damage, since sensory neurons are essential in protecting and maintaining our tissues throughout life.

The findings appear in the journal Cell Reports, titled “Intradental mechano-nociceptors serve as sentinels that prevent tooth damage.”

More than 6,000 years ago, in the Krumlov Forest of South Moravia in the Czech Republic, two sisters endured a hard life in an ancient mining settlement. Now, thanks to advanced forensic methods and archaeological research, their incredibly lifelike faces have been uncovered in new 3D reconstructions. These reconstructions give us not just a glimpse into their physical appearance but also into a society that may have exploited its most vulnerable members.

The remains were first discovered over 15 years ago during excavations at a Neolithic chert (flint) mine—specifically, Pit 4, one of hundreds discovered in the area, which is known for prehistoric mining activity from the Mesolithic to the Iron Age. The remains included two adult females buried one atop the other, with the older woman hugging a newborn baby on her chest. Next to them was a partially complete skeleton of a small dog. The females were likely sisters and were interred in the shaft in which they had labored, according to a paper published in Archaeological and Anthropological Sciences.

Dr. Martin Oliva, an archaeologist with the Moravian Museum and a co-author of the study, told Live Science that the location of the women’s graves within the mine suggests that the women likely labored there. The mine may have also had spiritual meaning, serving as a sacred site related to ancestral or sacrificial rituals, the researchers suggest.

Detailed analysis, involving radiocarbon dating, genetic analysis, isotopic analysis, and bone study, paints a grim picture of physical suffering and exploitation. Both women, estimated to have been around 30 to 40 years old, were around 1.48 and 1.46 meters (approximately 4.8 feet) tall and bore signs of heavy labor. The bones exhibited worn vertebrae, early arthritis, herniated discs, and partially healed fractures—specifically, one on the older sister’s forearm—indicating that they continued to work despite severe trauma.

Interestingly, isotopic analysis of nitrogen and carbon levels indicated that although the sisters had grown up malnourished and ill, in adulthood, they had consumed a high-meat diet. This was unusual for European Neolithic populations, which may have been due to better access to wild game in the densely forested region or a nutritional strategy to fuel their hard labor.

DNA testing confirmed the sibling relationship and even determined some physical features. The younger sister likely had dark hair and green or hazel eyes, while the older may have had blue eyes and blonde hair. These features were utilized for the lifelike facial reconstructions—on display today at the Moravian Museum in Brno—created using plaster, silicone, prosthetic eyes, and implanted hair. The skulls were in a good state and allowed for detailed facial modeling.

The reconstructions also depict clothing derived from Neolithic-era archaeological textile finds, made entirely of plant fibers like flax and nettles. The older woman wears a simple blouse and plant-fiber wrap, and a hairnet. The younger one wears a linen blouse with braided fabric strips woven through her hair.

But questions remain. The infant that was buried was genetically not related to either woman, and the positioning of the dog’s remains adds another question mark to the burial. Scientists have not ruled out that the women and infant could have been victims of ritual sacrifice or symbolic appeasement to the earth, as mining shafts could have had spiritual significance to Neolithic peoples.

In the broader social context, the authors point to a possible reorganization of work in the Neolithic period. The article contends that as soon as hierarchical societies began to emerge, “the hardest labour may no longer have been done by the strongest, but by those who could most easily be forced to do it.” This is a hint that even in early agricultural societies, labor might have been distributed in unequal forms, possibly on the basis of gender, age, or social status.