Teeth enamel is the most mineralized and hardest part of the human body. However, is soft when freshly laid down. The process of hardening is quite interesting. Now scientists from the University of Helsinki and Aalto University adapted the classical Stefan problem to explain how tooth enamel gets distributed over the crown during growth. The same methods help scientists explaining the formation of snowflakes.
The Stefan problem in mathematics helps analysing phase transitions in matter. Physicists and mathematicians use this principle to explain crystal formation. For example, Stefan problem can and is used to research snowflakes. Now scientists applied the same kind of methods to explain the distribution of enamel, which grows in different thicknesses around a tooth. This method allowed Finnish scientists to discover that differences in enamel thickness are regulated by the nutrient diffusion rate. In other words, different parts of a tooth receive nutrients, needed to make enamel, at different rates.
Scientists actually started with a model, which is made to research snowflakes. They just replaced ice with enamel matrix. Obviously, teeth enamel is nowhere near as complex and interesting and snowflakes, but they do have some similarities. For example, same physical principles can account for the increase in complexity in both systems. More than anything, this creates a new approach of analyzing enamel, which is important in both medical research and practice and paleontological examinations.
Simulations were started with CT-imaged real teeth from which enamel was digitally removed. Enamel was loaded into underlying dentin surfaces and then matrix secretion was simulated as a diffusion-limited process. In this way scientists analyzed the formation of enamel on human, orangutan and pig teeth. This allowed them to confirm that differences in enamel thickness are regulated by the nutrient diffusion rate. Jukka Jernvall, one of the authors of the study, said: “There are huge amounts of different data available on enamel, and now we have the tools of physicists to make testable predictions”.
This study does not create groundbreaking results. However, the knowledge that nutrient diffusion rates regulate the thickness of the enemal can be pretty useful. Furthermore, the method will be used in other studies both in medical science and paleontology.
Source: University of Helsinki