Are Teeth Stronger Than Bones? Finding the Toughest Substance in the Human Body

When it comes to the strength of our body’s structures, we often think of bones as being the strongest and most durable. But what about our teeth? Are they just as strong, or do they fall short when compared to our bones?

There are several debates on whether the teeth or the bone is stronger. Teeth are mainly used for breaking down food, the bones protect our organs, provide structure, and allow us to move.

The answer is the teeth, as its composition makes it the hardest substance in the human body. In particular, the tooth enamel, which is the outer covering of the tooth, is 95% minerals, 4% water, and 1% protein. The main mineral present (~90%) in the enamel is hydroxyapatite, a form of apatite which comprises of calcium, phosphate and water. It is this high percentage of hydroxyapatite that makes the teeth incredibly strong and durable.

Anatomy of the tooth | Image credits: Reason to Smile Dental

While hydroxyapatite is present in both the teeth and the bone, only 65% of the latter is made up of minerals. The remaining 35% are made up of organic substances such as type I collagen (~90%) and non-collagenous proteins (~10%). It is this organic component that gives bones their flexibility as compared to the teeth.

As we can see, the main difference between the teeth and the bone is the higher concentration of hydroxyapatite, and it is this difference that makes the former a much stronger material than the bone.

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As hydroxyapatite makes up over 90% of a tooth composition, toothpaste manufacturers have produced hydroxyapatite toothpaste to aid with the remineralization of the tooth.These toothpaste are made with synthetic hydroxyapatite (HAp), a biocompatible and bioactive material that was invented in the 1990s to replicate the organic hydroxyapatite. Some of the popular hydroxyapatite toothpaste in the market include:

  1. Boka Coco Ginger (Nano-Hydroxyapatite) Natural Toothpaste
  2. Davids Nano Hydroxyapatite Natural Toothpaste
  3. Apagard Premio (Nano-Hydroxyapatite) Toothpaste
  4. PerioSciences Natural Toothpaste
  5. Dr. Brite Healthy Smile Toothpaste

Strength of Teeth vs Bones

While we can conclude that the tooth is stronger than the bone, you may have wondered just how strong a tooth exactly is, and how it compares against the bone.

The amount of pressure that a bone can withstand can vary depending on a number of factors, including the type of bone, its density, and its size and shape. In general, however, it takes about 1700 pounds per square inch (PSI) to break the human femur.

For comparison, traditional concrete have a PSI ranging from 2,000 to 5,000 PSI while steel have a strength of 40,000 PSI.

The teeth, which are designed to tear through meat and tough plants, handles around 150 to 200 PSI when the teeth is clenched. However, the average human tooth can withstand up to 20,000 pounds of force before it breaks

As previously mentioned, the strength of the tooth is due to the high concentration of hydroxyapatite. This mineral belongs to a group of phosphate called Apatite which has a Mohs Hardness Scale of 5, making the tooth enamel the one of the hardest biological material on Earth.

Mohs Hardness Scale | Image credits: Bonz-n-Stone

The scale is a test designed to measure the hardness of a mineral, with 1 being the least hard (e.g Talc), and 10 being the hardest (e.g Diamond). For reference, iron and has a Mohs scale of 4-4.5 while glass measures 5.5 on the scale.

That said, the tooth enamel is more brittle than steel and can chip much more easily. Furthermore, the strength of the tooth is compromised when it suffers from demineralization, a condition where the minerals are attrited from organic acids produced by plaque.

Difference Between Teeth and Bones

While both share several commonalities including their color and composition, teeth are not bones. In fact, the teeth and the bones differs in several ways:

  • A broken bone is able to repair and heal itself whereas a tooth do not grow back if it is chipped.
  • Bones undergo modification and remodeling under stress. While a teeth can shift under certain circumstances (e.g grinding of teeth, braces), its structure remains largely unchanged.
  • Bones contains the bone marrow, a soft, spongy tissue. Bone marrow produces hematopoietic stem cells, an “immature” cell which transforms into red blood cells, white blood cells, and platelets. This is absent in the tooth.
  • Teeth are exposed while our bones are “tucked safely” under our skin.

It is important to note that the strength of a tooth or a bone can vary depending on many factors, such as the type of tooth or bone, the presence of any dental work, the overall health of the tooth or bone, and the density, shape, and size of the tooth or bone. Additionally, bones can become stronger with regular exercise and physical activity, while teeth can become weaker due to factors such as decay and injury.

In summary, both teeth and bones have unique properties that contribute to their strength, and they can withstand a significant amount of force before breaking. That said, one must maintain good oral hygiene and see a dentist regularly to ensure that teeth remain strong and healthy, and to engage in regular exercise and physical activity to keep bones strong and healthy.