Just like our bodies, teeth inevitably undergo changes as we age. To understand what exactly is happening to them, we first need to understand what they are made of.
The structure of the human tooth
The crown of the tooth (the part of the tooth that protrudes above the gum) is covered on the outside by hard enamel, which surrounds the slightly less hard and darker dentin, which in turn protects the soft pulp located in the very center.
Enamel has a very complex crystalline structure. Due to the interaction of crystals with light, teeth look so milky white, pearly.
Dentin is the hard tissue of the tooth that forms its base. Some of the dentin is on the crown of the tooth, and some is on the root, located deep in the gum. Dentin is made up of the mineral hydroxyapatite, protein organic material, and water. Dentin is permeated with elastic, resilient collagen fibers that prevent teeth from cracking and breaking down when we chew food.
The pulp is a loose connective tissue that contains a lot of nerve endings, blood and lymphatic vessels that connect the tooth to the rest of the body. The pulp also contains odontoblasts – specialized cells that form dentin.
Each tooth contains a certain number of odontoblasts, so dentin cannot be renewed indefinitely.
Dentin is also permeated with microscopic tubes called dentinal tubules, which connect the pulp and enamel. These tubules supply dentin with liquid nutrients coming from the pulp.
How Teeth Change with Age
Since dentin stops renewing itself and loses its elasticity, teeth become more fragile and can easily break. This is especially true for those teeth that have already experienced a lot in their life – they have cracks in the enamel, they have been affected by caries, they have been treated, filled, the root removed.
Over time, the outer layer of tooth enamel becomes thinner, and the comparatively darker dentin begins to show through, which darkens even more with age, causing the teeth to no longer be as snow-white as before. Dentin darkens with age because the collagen fibers become shorter and harder, and the fluid in the dentinal tubules mineralizes.
Teeth darken with age also because odontoblasts continue to form dentin inside the tooth, reducing the transparent cavity occupied by the pulp.
In addition, microparticles of coffee, tea, wine, food fill microcracks in the enamel, which leads to a change in its color. This can be combated with the help of special teeth whitening procedures.