Researchers from the University of Zurich have demonstrated that mutated genes lead to defects in tooth enamel, which can therefore encourage the development of caries.1

The researchers wanted to find out why some people develop caries even though they always brush their teeth carefully, while others are less stringent yet do not have any holes. Ultimately, both types of people have bacteria on the surface of their teeth which can attack the enamel; however, if the outer layer of the teeth is defective, caries can strike.

The researchers have now pinpointed a gene complex for the first time that is responsible for the formation of tooth enamel. Two teams from the Centre of Dental Medicine and the Institute of Molecular Life Sciences used mice with varying mutations of the enamel proteins involved in the so-called Wnt signalling pathway. Thanks to this transmission route, human and animal cells respond to external signals and specifically activate selected genes in the cell nucleus. The signalling pathway is essential for embryonal development and also plays a pivotal role in the development of cancer or physical malformations.

'All mice with mutations in these proteins exhibit teeth with enamel defects,' said Pierfrancesco Pagella, one of the study's two first authors. 'Therefore, we demonstrated that there is a direct link between mutations in the genetic blueprints for these proteins and the development of tooth enamel defects.'

The team of researchers was the first in the world to use modern genetic, molecular and biochemical methods to study tooth enamel defects in detail.

The hardness and composition of the tooth enamel can affect the progression of caries. 'We revealed that tooth decay isn't just linked to bacteria, but also the tooth's resistance,' says Thimios Mitsiadis, Professor of Oral Biology at the Center of Dental Medicine. Bacteria and their toxic products can easily penetrate enamel with a less stable structure, which leads to carious lesions, even if oral hygiene is good.

Understanding the molecular-biological connections of tooth enamel development and the impact of mutations that lead to enamel defects opens up new possibilities for the prevention of caries.