Are Teeth Stronger Than Bones?

Teeth are one of the strongest structures in the human body. However, 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. While it can be concluded that both are strong and durable, which is stronger, teeth or bones?

The answer is the teeth, as its composition makes it the hardest substance in the human body. The tooth enamel, which is the outer covering of the tooth, is made up of 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 a tooth 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%). As such, the higher concentration of hydroxyapatite in teeth makes it a much stronger substance than bones.

Over the years, companies have came up with hydroxyapatite toothpaste to aid with the remineralization of the tooth. The toothpaste are made up of synthetic hydroxyapatite which was invented in the 1990s to help fight against cavities. Some of the popular hydroxyapatite toothpaste in the market include Boka Coco Ginger Toothpaste, Davids Nano Hydroxyapatite Natural Toothpaste, Bite Fresh Mint Toothpaste Bites and Dr. Brite Healthy Smile Toothpaste.

How Strong Are Teeth?

While it can be concluded that the tooth is stronger than the bone, you may have wondered just how strong a tooth exactly is.

The teeth, which are designed to tear through meat and crush shells, can exert and withstand over 200 pounds of pressure. In a hydraulic press test conducted by Youtuber Hydraulic Press Channel, a tooth withstood 628 pounds of pressure before cracking.

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.

The 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.

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