Tooth

The tooth in vertebrates is a hard structure in the mouth, used for biting, crushing or tearing at food, and in defense and aggression.

In humans the first set, the milk teeth, appear from age six months to two-and-a-half years, and number 20.

The permanent dentition starts from the sixth year onwards. Adult humans have 32 teeth of three different-types (incisors, canines and molars).

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HISTORY

Our hunter-gatherers ancestors had much better dental health than us. Cavemen had relatively straight teeth and crooked teeth are a modern phenomenon.

The ancient Chinese, Egyptians and Mayans all experimented with artificial teeth screwed into the jawbone, but modern implants began in 1965. 

The phrase "By the skin of my teeth" comes from the Bible verse Job 19:20, in which Job states, "I am escaped with the skin of my teeth."

Medieval peasants had reasonably healthy teeth, which didn't deteriorate much because there was no sugar in their diet. Also there was a lot of grit in the bread they ate, which ground their teeth very flat. 

Muslims generally had better teeth than the Europeans because their religion told them to keep them clean. They achieved this by using a type of chewstick called a Siwak stick.

Queen Elizabeth I's teeth were turned black in her old age through eating too many sweet things. In fact black teeth were a status symbol in Elizabethan times as sugar was very expensive, costing nine times as much as milk.

In 1615 an early tooth whitening product was advertised in England. A sage and salt scrub was recommended to 'English huswives' as a way to achieve gleaming white teeth.

By the 18th century in Britain poor teeth was rife. Georgian women sometimes wore second hand teeth, fashioned into dentures, sold to them by the poor.

The Stanford Daily reported on April 12, 1928 that Mathias Blau of Chicago convinced his wife to have all her teeth pulled. He then refused to buy her dentures because it was "cheaper to feed her soup than solid food." Mrs Blau took him to court and her husband was told to get her two new sets of teeth and at least a beef steak a week. 

Fluoridation of water was introduced in the USA to prevent tooth decay in 1945. Experiments have indicated that a concentration of fluoride salts of 1 part per million in tap water reduces by over half the decay of children's teeth.

British Columbia woodsman Francis Wharton shot a deer in the late 1960s but had no serviceable teeth with which to eat it so he fashioned dentures out of the deer's own teeth. 

HUMAN TEETH

Though your teeth are considered part of your skeletal system they are not in fact considered bones. 

Diagram of a healthy human molar. By KDS4444 

Tooth enamel is the hardest substance in the human body. It's composed of mineralized calcium phosphate, which is the single hardest substance any living being can produce. Your tooth enamel is harder than a lobster's shell or a rhino's horn.

Human teeth are almost as hard as rocks.

Human teeth can detect a grain of sand 1/2,500 of an inch in diameter.

Teeth are only able to experience one sensation, that being pain. When you eat or drink something too hot or too cold, or a dentist operates on your teeth, you will only experience pain because that is the only thing the nerves around your teeth respond to.

One baby in every 1,000 is born with teeth.

It is trendy for youth in Japan to attain uneven snaggle teeth known as "yaeba," or "double tooth."

Humans have 12 molars in total, in four groups of three at the back of the mouth. The molar, which is the farthest back in each group and is the last to appear, is called a wisdom tooth. 

Wisdom teeth get their name because they emerge into the mouth when people are in their 20s, affectionately termed the "Age of Wisdom."

Wisdom tooth By Coronation Dental Specialty Group

The oldest person to grow a new tooth is American Erna Kohane, who managed the feat when she was 92 years and 144 days old in 2014. 

Another American, Joyce Walen, holds the record for having the oldest baby tooth — she still had it when she was 87.

Yellow teeth are stronger, the natural color of our teeth is a light yellow color. Whitening your teeth can permanently weaken them.

People who drink three or more glasses of soda each day have 62% more tooth decay, fillings and tooth loss than others.

Kissing is good for teeth. The anticipation of a kiss increases the flow of saliva to the mouth, giving the teeth a plaque-dispersing wash.

We produce a lot of saliva just before vomiting in order to protect our teeth from erosion due the acidity of vomit.

ANIMAL TEETH

Limpet teeth have the highest tensile strength among biomaterials, outperforming spider silk.

The animal with the most teeth is the slug. They have a flexible band of thousands of microscopic teeth, called a radula. 

Slugs average approximately 27,000 teeth – one species of umbrella slug, Umbraculum, can have up to 750,000 teeth.

Opossums have fifty razor sharp teeth, the highest number of teeth found in any land mammal.

An alligator has about 80 teeth in its mouth at one time and can go through over 2,000 teeth in a lifetime.

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The African Elephant has only four teeth, 5 kg each.

Beavers have four razor-sharp incisors for cutting and 16 back teeth for chewing. Their front teeth never stop growing.

A guinea pigs' teeth never stop growing. They constantly have to grind them down on toys or other things.

Fish communicate with each other by rasping their teeth to make sounds in their throat.

Sloane's viperfish holds the world record for largest teeth relative to head size in a fish. It has teeth so large that it must open its mouth to make the jaws vertical before it can swallow prey.

Source Daily Mail