Tooth Enamel is the Hardest Substance in the Human Body.

Here’s How it Stacks Up.

Your amazing, versatile, complicated body is tougher than it looks. Between your muscles, skin, cartilage, and bones, your vital organs are surrounded by a structural force field that doubles as an engineering marvel. So what’s the hardest substance in your body? The answer might surprise you. In fact, the most durable and tough substance in your body is actually a tissue. Encasing your teeth and helping you chew, bite, and tear your food is your tooth enamel. That’s the hardest substance in the human body.

What is tooth enamel?
Enamel is 96 percent densely packed minerals, which is more mineral than any other tissue your body creates. This makes enamel the perfect protector for your teeth, whether you’re gnashing on jerky or drinking a hot beverage. Just how hard is enamel? At the atomic level human tooth enamel is incredibly complex. It consists of tightly bunched together, oblong-shaped mineral crystals that are a thousand times smaller than a strand of your hair. According to the Mohs Hardness Scale, tooth enamel earns a 5. That means it’s about as hard, or harder, than steel. For reference, diamonds are the strongest substance on earth, ranking 10 on the Mohs scale.

What about human bones?
You might have assumed that bones are the hardest substance in your body. And bones are incredibly tough, also earning a 5. Bones are considered to be stronger than concrete. Fun fact: the jawbone and the femur are considered the strongest bones in your body. Bone is made of living tissue. Collagen and a mineral called calcium phosphate make up most of your bone structure. The unique composition of your bones is what makes them strong and resilient, but flexible enough to absorb some stress.
• Cortical bone tissue is dense, and it makes up the outer layers of your bones.
• Trabecular bone tissue is the spongy, honeycomb-like material that makes up your inner bones.

What about muscles, ligaments, and other body tissues?
Muscles, ligaments, and tendons are also incredibly strong, although they aren’t made up of the hardest materials in your body. Muscles, ligaments, and tendons are incredibly strong and have varying degrees of elasticity. But they aren’t particularly hard, and would rank low on Mohs scale.
Muscles are made of thousands of highly flexible fibers. Muscles help your bones to move, and also form the walls that surround your organs. Muscle fibers are bound together tightly in groups, which is what gives them strength.
Ligaments are made of strong, connective collagen tissue. These bands of tissue are used to hold your joints together and keep your muscles in place throughout different parts of your body. Ligaments are like ropes that keep your muscles from over-extending their reach.
Tendons are also made of connective collagen fibers. Tendons are what connect your muscles to your bones. Tendons are more flexible than ligaments. They also contain fewer blood vessels than your muscles, which makes them more prone to injury.

If enamel is so tough, why do we still get cavities?
Cavities in your teeth come from a combination of four factors present all at the same time: Carbohydrates (sugar) in contact with the surface of your teeth, a compromised tooth surface, a specific bacterial strain, and time. Still, it seems incredible that a tiny, seemingly weak and soft thing like bacteria could have any hope against your enamel. If you can’t scratch your enamel with a fingernail, how can a little bacteria have any hope of doing any damage to this extremely hard, seemingly impervious substance? The answer is that the bacteria doesn’t directly “eat” your teeth. Instead, bacteria clump together and stick to the surface of your teeth in a substance called plaque. Over time, the bacteria eat the sugar and convert it to acid. The acid, in turn, causes the de-mineralization of the tooth surface. Once the pH of your saliva drops to 5.5, your tooth enamel will begin to be de-mineralized. So, as you can see, keeping your teeth clean by brushing, flossing and twice-yearly dental cleanings is essential to great oral health.

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