50 Fun Facts About Teeth

How many teeth are in a full set of adult human teeth?

That includes the four wisdom teeth, which many people have removed or never grow at all.

How many baby teeth does a child usually get?

They start forming in the embryo at six to eight weeks and begin poking through around six months after birth.

What is the hardest substance in the human body?

It is about 96 percent mineral and rates a 5 on the Mohs hardness scale, about the same as a steel knife blade.

Why can the damaged outer layer of a tooth never grow back?

The ameloblast cells that build the layer are destroyed once the tooth erupts, so a cavity is permanent until a dentist fills it.

How many molars, including wisdom teeth, does a full adult mouth contain?

The rest of the set is eight incisors, four canines and eight premolars.

Wisdom teeth are the third molars. Between what ages do they usually come through?

The Latin name is dens sapientiae, and they are the most commonly impacted teeth in the mouth.

Which human teeth have the longest roots?

Canines are also the only teeth with a single cusp, and they are nicknamed eye teeth because they sit beneath the eyes.

Canine teeth are named for being especially prominent in which animal?

Humans have four; in many species the males' are far larger and used for display and fighting.

What is the technical name for a gap between two teeth, like the one Madonna has?

The French call them dents du bonheur, lucky teeth, and in Nigeria and Ghana the gap is considered attractive.

Below what pH does mouth acid begin dissolving a tooth's outer mineral layer?

The bacterium Streptococcus mutans turns sugar into lactic acid, which is why sweets and decay go together.

Which bacterium is the main culprit behind tooth decay?

As of 2016 roughly 3.6 billion people, almost half the planet, had cavities in their permanent teeth.

The narwhal's famous spiral tusk is actually what?

It projects from the left side of the upper jaw, can reach three metres and holds millions of nerve endings.

In medieval Europe, narwhal tusks were sold as what?

At the peak of the trade a tusk could fetch hundreds of times its weight in gold.

About how many teeth does a great white shark have at any one time?

They sit in rows like a conveyor belt, and some shark species shed around 35,000 teeth in a lifetime.

The largest known shark teeth, more than seven inches tall, belonged to which extinct species?

Fossil collectors pay steep prices for them; Dunkleosteus was an armoured fish with bony blades rather than teeth.

A snail carries thousands of microscopic teeth on a ribbon-like organ called what?

It is made of chitin and works like a rasp; limpet versions contain iron and rank among the strongest biological materials known.

Which group of molluscs has no rasping tongue-ribbon at all?

Clams and oysters filter-feed with cilia instead of scraping.

An elephant's tusks are enormously overgrown versions of which kind of tooth?

They are the second upper incisors; about a third of each tusk is hidden in the skull, and they keep growing around 17 cm a year for life.

How many sets of molars does an elephant go through in its lifetime?

New sets move in from the back; once the last set wears down in an elephant's forties, it can starve.

What defines a rodent's teeth?

The word rodent comes from the Latin rodere, to gnaw, which they must do constantly to keep the incisors short.

A rodent's gnawing teeth stay razor sharp because the hard coating covers only which side of them?

The softer dentine behind wears away faster, leaving a chisel edge without any effort.

Which animal's teeth are made of thin hexagonal tubes, giving its order the name Tubulidentata?

It is born with incisors and canines that fall out and are never replaced, leaving only cheek teeth that regrow continuously.

How often can a crocodile replace each of its roughly 80 teeth over its lifetime?

A small replacement tooth waits beside every full-grown one; unlike an alligator, all its teeth show when the mouth is shut.

How long can a hippopotamus's lower canine teeth grow?

The jaw hinge sits so far back that a hippo can open its mouth to 100 to 110 degrees.

What does a giraffe have instead of upper front teeth?

It strips leaves with a 45 cm dark tongue instead, which may be dark to protect against sunburn.

Which French physician's 1728 book The Surgeon Dentist earned him the title "father of modern dentistry"?

He disproved the ancient tooth-worm theory, blamed sugar acids for decay and described braces made of gold wire.

For thousands of years, what did people in Sumer, Egypt, India and China believe caused toothache?

The idea only died out after early microscopists went looking and found nothing.

In which country was the oldest known dental work, a 14,000-year-old cleaned tooth, found?

Stone-age dentists at Mehrgarh in what is now Pakistan were drilling teeth with bow drills around 7000 BC.

The first named dentist in history, Hesy-Ra, practised in the 27th century BC in which civilisation?

During the Middle Ages the job passed to barber-surgeons, who mostly just pulled teeth.

The world's first dental college opened in 1840 in which American city?

The Baltimore College of Dental Surgery invented the DDS degree and is now part of the University of Maryland.

What were George Washington's dentures made from?

The wooden myth probably arose because the ivory stained brown; he had one natural tooth left at his 1789 inauguration.

The Etruscans made partial dentures from the 7th century BC by fastening teeth with bands of what?

Porcelain false teeth arrived around 1770 and hardened-rubber vulcanite bases in the 1850s.

Which American city was the first in the world to add fluoride to its water supply, in January 1945?

The idea grew out of Frederick McKay's study of the "Colorado brown stain", whose sufferers had oddly cavity-free teeth.

What fluoride level in drinking water did the US Public Health Service recommend in 2015?

The 2015 figure replaced the older 0.7-1.2 mg/L range; the CDC named water fluoridation one of the ten great public health achievements of the 20th century.

The first bristle brushes for teeth, hog bristles on bamboo or bone handles, came from which country?

That was during the Tang dynasty; before that, people in Sumer used frayed twigs called chew sticks as far back as 3500 BC.

The first nylon-bristle brush for teeth went on sale in 1938, made by which chemical company?

The first electric toothbrush, the Broxodent, followed from Switzerland in 1954.

In a 2003 MIT survey, which everyday invention did Americans say they could least live without?

It beat the car, the computer and the phone.

Which company first sold toothpaste in jars in 1873, and later adopted the collapsible tube?

The tube itself was inspired by paint tubes and invented by dentist Washington Sheffield in 1880.

The first fluoride toothpaste to win American Dental Association approval was which brand?

Procter & Gamble developed it in the 1950s with researcher Joseph Muhler at Indiana University.

In 1819, dentist Levi Spear Parmly recommended flossing with waxed thread made of what?

Johnson & Johnson patented floss in 1898 using suture silk; nylon took over during World War II.

In 1844 dentist Horace Wells had his own tooth pulled to demonstrate which anaesthetic?

"I didn't feel it so much as the prick of a pin," he said; his Boston demonstration a month later went wrong and he was mocked as a humbug.

In Spain and much of Latin America, which character collects children's lost teeth instead of a fairy?

The little mouse was invented in 1894 by Luis Coloma in a story for the eight-year-old King Alfonso XIII.

The earliest known mention of the tooth fairy came in a 1908 column of which newspaper?

A 1927 play by Esther Watkins Arnold gave her the elf-like form kids picture today.

According to Delta Dental's survey, what did the tooth fairy pay per tooth in the US in 1998?

The going rate peaked at $6.23 in 2023 before slipping to about $5 in 2024-25.

Who identified Joseph Warren's body in 1776 by a dental prosthesis he had made, America's first forensic dental ID?

The silversmith made false teeth on the side; teeth remain useful to forensics because they survive fire and decomposition.

Which serial killer's murder conviction relied partly on now-discredited bite-mark evidence?

The National Academy of Sciences and others have since concluded bite marks cannot reliably identify a person.

The Nitinol wire used in modern braces was created in 1959 by which organisation?

The nickel-titanium alloy has shape memory; orthodontist George Andreasen started using it in 1979.

What term describes animals like humans that develop two sets of teeth in a lifetime?

Most mammals are diphyodont; the first primary teeth usually erupt at around six months of age.

Which yellowish tissue makes up most of a tooth, beneath the enamel?

Dentin is about 70% inorganic material by weight and is secreted by the odontoblasts of the dental pulp.

Premolars are also known by what other name?

Humans have four tooth types: incisors cut, canines tear, and premolars and molars crush food.