New research may expedite regenerative dentistry

Even though major tooth cell types have long been identified, the spectrum of various tooth cells and stem cells, their differentiation, and the interactions that enable tooth growth remain poorly understood. Teeth develop through a complex process in which soft tissue, with connective tissue, nerves and blood vessels, is bonded with three different types of hard tissue into a functional body part.

In contrast to humans, whose teeth are completed before adulthood, mice and many other species have teeth which continue to grow throughout life. The incisor stem cell population in mice continuously self-renews and replenishes tissue that is lost owing to gnawing, making this model attractive for studies of stem cell generation, cell differentiation and injury-induced regeneration.

Mapping of dental cell populations

Using a single-cell RNA sequencing method and genetic tracing, the researchers examined the characteristics of growing mice incisors, compared them with non-growing mice molars and evaluated the extent to which the mouse model reflects the growth of human teeth. In this manner, the researchers at Karolinska Institutet, in collaboration with the Medical University of Vienna in Austria and Harvard University in the US, identified and characterised all cell populations in mouse teeth, in young growing human teeth and in adult human teeth.

“From stem cells to the completely differentiated adult cells we were able to decipher the differentiation pathways of odontoblasts, which give rise to dentine […] and ameloblasts, which give rise to the enamel,” said the study’s senior author, Dr Igor Adameyko, senior researcher in the Department of Physiology and Pharmacology at Karolinska Institutet, and co-author Dr Kaj Fried, senior professor in the Department of Neuroscience at Karolinska Institutet, in a press release. According to them, they also discovered new cell types and cell layers which may play a role in tooth sensitivity.

In addition, the findings might explain complex aspects of the immune system in teeth and help in understanding the formation of tooth enamel. “We hope and believe that our work can form the basis of new approaches to tomorrow’s dentistry. Specifically, it can expedite the fast-expanding field of regenerative dentistry,” added the authors.

The study, titled “Dental cell type atlas reveals stem and differentiated cell types in mouse and human teeth”, was published online on 23 September 2020 in Nature Communications.

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