We all know getting a tooth cavity is a nightmare. Did you ever wonder why teeth can’t repair their damages on their own like skin or bones do?
The answer to this question is presented in-detail in the four explanations below.
Essentially, it’s because there is no mechanism to get resources and healing cells up to the crown of your teeth. The roots are surrounded by blood vessels that can deliver healing resources, but there is no blood going to the top of your teeth.
Your saliva can provide a limited amount of healing to the enamel because of the calcium in contains, but it’s very minor, and more of a maintenance process, rather than true healing.
Teeth can sort of heal. There are three layers to the crown of a tooth: enamel on the outside, dentin under that, and the dental pulp at the core. The dental pulp constantly produces dentin throughout life (very slowly) and sometimes produces dentin in response to a bacterial assault on the tooth (i.e. cavities). If the pulp manages to lay down enough new dentin from the inside, it can prevent a pulp exposure, which would necessitate a root canal or extraction.
The enamel, however, cannot regenerate. The cells that produce enamel (called ameloblasts) all die before the teeth erupt. Weak spots in the enamel can remineralize via fluoride toothpaste, but new enamel cannot be produced. Once bacteria and acid have eaten their way past the enamel, the tooth must be cavity prepped and filled before the infection reaches the pulp, as dentin is much softer and more permeable than the enamel.
The enamel is the hardest substance in the human body, and also has the highest percentage of inorganic material (96% I think). That is the key, it’s inorganic, where as the rest of the tooth is organic and can be repaired.
Basically during tooth development, a bunch of cells (ameloblasts) lay down these really hard crystalline structures surrounding and protecting the softer, more organic parts of the teeth. After they have created them, the ameloblasts die off.
It’s weird to think about it this way, but enamel is like a stone covering for your teeth. It’s not really “human” like your other body parts are. It’s closer to a crystal you might find in a cave somewhere. You can’t add anything to or repair a crystal. You can however add chemicals to it to form a different type of crystal. This is what fluoride does. The crystal in enamel is called hydroxyapatite, and with the addition of fluoride, it forms fluoro-hydroxyapatite, which is a lot stronger and more resistant to decay.
During tooth development, internal usage of fluoride can be helpful, whereas once the tooth is formed, direct surface application via toothpaste or mouthwash is more useful. So brush your teeth twice a day kids!
Although our teeth can’t really repair themselves… There may be something that can help them to do so.
There is an Alzheimer’s drug that had shown the ability to encourage a tooth to regrow dentine. This could drastically reduce the need for a lot of expensive dental work. Sounds like the drug is put into a sponge material and applied to the tooth which will then regrow dentine that replaces the sponge and fills the cavity. Unfortunately, it hasn’t been tested on humans yet.