Why are teeth not considered bones?

At first glance, teeth look a lot like bones; Both are white, hard and rich in calcium. But why are teeth not considered part of the skeletal system? Despite the apparent similarities, these two structures have fundamental differences.

The main similarity between teeth and bones is in their composition: both are made of hard tissues composed of minerals such as calcium, phosphorus, fluoride and magnesium. At the molecular level, these minerals form a compact crystalline structure that makes teeth and bones much harder than other parts of the body.

“They’re both mineralized tissues, but honestly, that’s where the similarities end,” says Edmond Hewlett, professor emeritus of the UCLA School of Dentistry.

One of the reasons why teeth are not considered part of the skeletal system is the difference in their function from bones. Hewlett explains that the primary function of teeth is to grind food, although it also plays an important role in speech production. For this reason, teeth are part of the digestive system.

In contrast, bones have other functions. They provide structure and support to the body, provide attachment points for muscles, and protect vital organs such as the heart and lungs. Also, bones are the place of production of red and white blood cells; Red cells carry oxygen in the body and white cells play an essential role in the immune system.

Of course, there is a slight overlap in the function of teeth and bones. For example, the jawbones play an important role in maintaining the teeth and the chewing process. “They work together, but they’re separate,” says Hewlett.

Since teeth and bones have different functions, their structure is also different from each other. The outermost part of the teeth is made up of enamel, a very thin but extremely hard layer of mineral tissue. Enamel is the hardest substance in the body, a property that results from compact crystals of a combination of calcium and phosphate.

Underneath the enamel is the ivory; A type of mineral texture that is a little softer than enamel but still hard and resistant. Dentin forms the bulk of the tooth structure and contains microscopic tubules that house blood vessels and nerve endings. In the center of the tooth is the pulp, a jelly-like substance that is the place where blood vessels and nerves pass and helps to nourish and sense the tooth.

In contrast, bone structure is completely different. Bones are covered with a very thin and strong layer called periosteum, which contains blood vessels and nerves vital for tissue growth and repair. Under this layer, dense and compact bone tissue is located. Inside the bone is also spongy tissue (cancellus), a light and porous tissue that contains bone marrow and where new blood cells are produced.

One of the key differences between teeth and bones is that, unlike teeth, bones have blood vessels and nerves both on the outside and inside. This is because bones are living tissue, while teeth are not.

During embryonic and early childhood, teeth are formed from specialized cells called ameloblasts and odontoblasts. These cells form layers of enamel and dentin that harden over time. After finishing this process, the enamel producing cells are destroyed; For this reason, if a part of the tooth breaks or fills up, it cannot be restored naturally. Although the pulp inside the tooth is still alive, it cannot regenerate the outer layers of enamel or dentin.

In contrast, bones are dynamic and changing structures. They have a network of blood vessels, nerves, and living cells called osteoblasts and osteoclasts, which build new bone and break down old tissue, respectively. This continuous cycle of remodeling allows bones to repair after a fracture and adapt to physical changes such as increased or decreased physical activity. In fact, most of the skeleton of the adult human body is completely rebuilt every 10 years.

“Bone is a living part of the body,” Hewlett concludes. But take care of your teeth, because they won’t grow back.”