Teeth and bones are often thought similar. Both are white, hard, contain a lot of calcium, and are key structural components of the body, serving important roles. These similarities have led many people to ask: are teeth bones?
Despite their similarities, which will be explored further momentarily, teeth are not bones.
There have, however, been times when bones have served as teeth. Many early attempts at false teeth were carved from animal bones. Given that bones, while not as hard as teeth, are still sturdy substances, it makes sense that early attempts to replace teeth would use bones to do so.
However, this is the only way teeth and bones can be synonymous. To understand why the two are not the same, it is important to know what we mean by bones and teeth.
What is a Bone?
Bones are living tissues
Bones are living tissue. They are organs of the body, making up the axial and appendicular skeleton in vertebrate organisms. They serve many functions ranging from supporting the rest of the body to producing blood cells, storing minerals, and much more.
Bones can regenerate themselves
If a bone is broken, it can repair itself over time, sometimes to the point of being stronger than before it was broken.
Bones are composed primarily of the protein collagen and the mineral hydroxyapatite. The collagen serves as scaffolding for the bone. The hydroxyapatite is composed of calcium, phosphorus, oxygen, and hydrogen with a chemical formula of (Ca)10(PO4)6(OH)2]. It is this mineral that gives bone its mineralized, firm shape.
Bones are flexible
Bones are not completely rigid, however. If they were, they would shatter on slight impact, even from simply moving or walking.
Instead, they are flexible to absorb some of the shocks of the body’s movements.
Some bones are more flexible than others, depending on what they are designed to do. There are several major types of bone, and each has its quirks.
Long bones are what we think of when we think of bones and include things like the tibia, radius, and ulna. They compose the bones of the arms and legs.
Hollow in the middle and filled with bone marrow which is used to make different types of blood cells, long bones have specially fitted joints at each end to allow them to move correctly for each given joint.
Because long bones must increase in length during development, there is a special structure on the ends of the bone called the epiphyseal plate. The long bones grow in length using these plates. Without these plates, vertical growth would not be possible.
Flat bones form much of the internal skeleton of the boy, such as ribs and skull bones. They are designed to encase valuable organs such as the heart, lungs, and brain. They have marrow at the center, like long bones, and have a strong structure to protect vital organs.
Short bones are square or rectangular and provide flexible movement and support.
Many of the bones in the hands and feet are short bones. There are not very many short bones in the body.
The irregular bones consist of the rest of the bones in the body. These have no specific shape, instead varying to fit their tasks. Often, they serve as attachments for muscles, ligaments, and tendons.
Sometimes, where ligaments or tendons rub against something, small bones, called sesamoid bones, will arise. These are randomly distributed across individuals, with everyone having different sesamoid bones.
The average adult human has 206 bones, give or take a few, due to sesamoid bone formation and fusion of some bones in development. 80 of them are axial, while 126 appendicular.
What are teeth?
Teeth are isolated to one area of the body and come in four variants.
Like bones, they contain lots of calcium. They are used to tear apart food as it is consumed, making the food easier for the stomach and intestines to digest.
In humans, children develop primary or baby teeth. They are eventually replaced by adult or permanent teeth. Most adults have 32 teeth.
Also read: What Are Naturally Perfect Teeth?
Four kinds of teeth
While there are four kinds of teeth, the major differences are the location and shape of each tooth.
- Incisors: Incisors are designed to cut through food as it enters the mouth and reside at the front of the mouth.
- Canine: Beside incisors are the canine or cuspid teeth which usually are the biggest, most noticeable teeth.
- Premolars: Behind them are the bicuspids or the premolars. These teeth are involved in crushing food into a semi-paste that is more easily swallowed, a process completed by the molars.
- Molars: At the back of the mouth, the molars grind the food even more until it can be easily swallowed. Sometimes the rearmost molars, known as wisdom teeth, crowd the other teeth and need to be removed.
Different parts of a teeth
Teeth grow out of the jawbone and consist of four major parts and several supporting parts.
- Each tooth has a root, which reaches back to the jawbone and connects vital blood vessels to the tooth’s interior.
- The root is covered in cementum. Composed mostly of the same material as bone, cementum attaches ligaments to the tooth to prevent it from wiggling.
- Inside the tooth is what is termed dental pulp. This specialized tissue contains nerves and blood vessels that the tooth uses to supply vital nutrients. The pulp also contains a specialized type of cells called odontoblasts. These cells form and maintain dentin, another important component of teeth. Due to the increase in dentin, the area inside the tooth occupied by the pulp consistently shrinks over the life of the tooth.
- Dentin serves as the inner layer of teeth. It is similar in structure to bone and has a similar composition but has some unique proteins. Because it is less dense than the enamel that covers it, dentin makes an excellent support material for the hard, inflexible outer enamel.
However, this does make it more vulnerable to cavities.
Resting atop the dentin is the enamel, the part of the tooth visible to the eye. Enamel is the hardest substance in the human body, harder even than bone due to its high level of mineralization.
However, unlike bone, which is made of cells, the enamel is not cellular. Instead, it is a crystalline mineral structure, lacking blood vessels, nerves, and collagen. Because it is not living, enamel does not self-repair as bone does once it is formed.
Chipped enamel, either from sports, food, or some other accident, will remain chipped, barring a dental procedure.
Teeth: the most common of vertebrate fossils
The hardened, mineralized secretions of the teeth explain why the most common vertebrate fossil finds are teeth. Because the enamel and dentin make teeth very sturdy, they appear to be the most likely part of the body to survive the rigors of burial and fossilization, with shark teeth being among the most common of all vertebrate fossils.
Because bones are less mineralized and softer and contain more living tissue to decay, they are harder to fossilize than teeth.
Teeth and Bones: Similarities and Dissimilarities
Hard mineralized substance
The primary mineral is hydroxyapatite
Composed primarily of minerals
Do not self-heal if broken
Do not contain marrow
Do not produce blood cells
Can get cavities
Hard mineralized substance
The primary mineral is hydroxyapatite
Composed primarily of proteins
Self-heal if broken
Produce blood cells
Do not get cavities
Are Teeth Bones?
With the very brief overview of teeth and bones out of the way, it is finally possible to answer the question, are teeth bones?
At first glance, it would appear that they are. Teeth and bones share similar mineral and protein compositions. Teeth grow out of bones. Both are also hollow on the inside and are fed with blood vessels and nerves. However, there are some particularly important differences as well.
If a bone is broken, it can regenerate. Adult teeth do not regenerate if they are damaged or broken. The reason for this difference is bones are composed of cells. If a bone breaks, it makes new cells to fill the gap. If a tooth breaks, the enamel cannot make new cells to fix the break.
The only truly living part of the tooth is the pulp. The rest is largely mineral secretions. This is why teeth get cavities but bones do not.
Further, while both bones and teeth are hollow, teeth lack the marrow that bones use to manufacture blood cells.
This information leads to the inescapable conclusion that bones and teeth are different. Teeth are not bones. Instead, they are specialized mineral structures designed to prepare food for digestion. While they derive from bone and share many similarities with bone, they are different enough to be classified as a unique type of structure.
Victor E Arana-Chavez and Luciana F Massa. Odontoblasts: the cells forming and maintaining dentine. International Journal of Biochemistry and Cell Biology. 2004 Aug;36(8):1367-73.
Oregon State University. Bone Health In Depth. Accessed on December 5, 2022.
John Hopkins Medicine. Anatomy of the Bone. Accessed on December 5, 2022.