A UNIVERSAL annoyance: “Why does my brother eat the same amount of sweets as me and never get a cavity and I always need loads of fillings?"
Well now scientists have been looking into the reason. It appears that mutated genes can lead to tooth enamel not forming properly and leaving it more prone to decay. So each person's level of resistance to tooth decay differs as their tooth structure is microscopically different.
Enamel forms due to a process called amelogenesis and hardens by mineralisation. When certain enamel proteins are present it signals the tooth to increase the hardness of enamel and the rate of formation. However if there's a problem, too much enamel protein can be released and this can result in pitted and chalky enamel that is more prone to fracture, wear and decay.
Tooth enamel can give a particularly telling portrait of physiological events in the body, since the enamel is laid down in a regular, ring-like fashion, starting from the second trimester of pregnancy. Disruptions in the formation of the enamel can also be caused by disease, poor diet or psychological stress and show up as grooves on the tooth surface.
Researchers from the University of Zurich have now pinpointed a gene complex for the first time that is responsible for the formation of tooth enamel. They looked at enamel formation in mice and found that mutations in proteins trigger defective tooth enamel. There are three main proteins involved in telling the body to lay down enamel, so if these proteins aren't working properly then the structure of the enamel changes. The hardness and composition of the tooth enamel can affect the progression of cavities.
"All mice with mutations in these proteins exhibit teeth with enamel defects," explains 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." This genetic discovery goes a long way towards improving our understanding of the production of tooth enamel.
"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. This means that some people will have to pay extra attention to their diet and tooth cleaning regime to give their teeth the best chance of remaining as strong as possible.
