49 Fun Facts About Teeth

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

32: sixteen in each jaw, including the four wisdom teeth, which many people have removed or never grow at all.

How many baby teeth does a child usually get?

20 primary teeth, ten in each jaw; they start forming in the embryo at six to eight weeks and begin erupting around six months after birth.

What is the hardest substance in the human body?

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

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

Enamel contains no living cells: the ameloblasts that build it are lost 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?

Twelve: three molars in each quadrant, the third being the wisdom tooth; the rest of the 32 are eight incisors, four canines and eight premolars.

Which human teeth have the longest roots?

The upper canines have the longest roots of any human tooth; canines are the only teeth with a single cusp and are nicknamed eye teeth because the upper ones sit beneath the eyes.

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

Dogs: canine comes from Latin canis, dog, whose fangs are especially prominent; humans have four canines, and 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?

A diastema is a gap between two teeth, most often the upper front pair; 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?

Below pH 5.5, the critical pH, enamel's hydroxyapatite starts to dissolve; Streptococcus mutans turns sugar into lactic acid, which is why sweets and decay go together.

What is the soft tissue at a tooth's core, carrying its nerve and blood vessels, called?

The pulp fills the chamber at the centre of a tooth with nerves and blood vessels that enter through the root tip; a cavity that reaches it is what makes a root canal necessary.

The narwhal's famous spiral tusk is actually what?

The tusk is an elongated canine tooth that projects from the left side of the upper jaw; it can reach three metres and holds millions of nerve endings.

In medieval Europe, narwhal tusks were sold as what?

Narwhal tusks were sold as unicorn horns, prized as a cure for poison; at the peak of the trade a single tusk could fetch many times its weight in gold.

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

Around 300, set in several rows that move forward like a conveyor belt as front teeth are lost; 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?

Megalodon, extinct for about 3.6 million years, left teeth over seven inches tall that fetch steep prices from collectors; 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?

The radula is a chitinous ribbon that works like a rasp; limpet versions are hardened with iron and rank among the strongest biological materials known.

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

Bivalves such as clams and oysters lost the radula entirely; they filter-feed with cilia on their gills 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?

Six sets: new molars move forward from the back of the jaw like a conveyor belt; once the sixth and final set wears down in old age, the elephant can starve.

What defines a rodent's teeth?

Two pairs of ever-growing incisors, one upper and one lower, define rodents; the name comes from 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?

Enamel covers only the front face of a rodent's incisors; the softer tissue behind wears away faster, leaving a self-sharpening chisel edge.

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

The aardvark is the only living member of Tubulidentata; it is born with incisors and canines that fall out unreplaced, leaving rootless cheek teeth of hexagonal tubes that grow continuously.

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

Up to 50 times: a small replacement tooth waits beside every full-grown one, so a crocodile can go through several thousand teeth; unlike an alligator, its lower teeth show when the mouth is shut.

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

Up to 50 cm: the lower canines are weapons rather than feeding tools, kept sharp by grinding against the upper canines; hippos crop grass with their broad lips.

What does a giraffe have instead of upper front teeth?

A hard palate, or dental pad, meets the lower incisors, as in cattle; the giraffe strips leaves with a 45 cm dark tongue whose colour may protect against sunburn.

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

Pierre Fauchard's Le Chirurgien Dentiste (1728) blamed sugar acids for decay, described fillings and gold-wire braces, and set dentistry out as a profession in its own right.

What is the medical term for habitually grinding or clenching the teeth, often during sleep?

Bruxism is the clenching or grinding of teeth, often during sleep; it wears enamel flat and can cause jaw pain and headaches, and a night guard is the usual treatment.

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

Italy: a 14,000-year-old molar from Riparo Villabruna in the Dolomites had decay scraped out with a flint tool; Stone Age dentists at Mehrgarh in modern Pakistan were drilling teeth with bow drills around 7000 BC.

Which official under Pharaoh Djoser is the first dentist named in history?

Hesy-Ra, an official under Pharaoh Djoser around 2600 BC, bore the title chief of dentists and physicians, which makes him the first dentist named in history.

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?

Hippopotamus ivory carved to hold human and animal teeth, held together with metal springs and wire; the wooden myth probably arose because the ivory stained brown, and 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?

Gold: Etruscan dental appliances from the 7th century BC held replacement teeth, sometimes from oxen, in bands of soft gold; porcelain false teeth arrived in the 1770s and vulcanite rubber bases in the 1850s.

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

Grand Rapids, Michigan began fluoridating on 25 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?

0.7 mg/L: the 2015 recommendation 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?

China: hog-bristle brushes on bamboo or bone handles appear under the Tang dynasty; long before that, people in Babylonia used frayed twigs called chew sticks as far back as 3500 BC.

The first nylon-bristle toothbrush, sold in 1938, used fibre from which chemical company?

DuPont's new nylon supplied the bristles for Dr. West's Miracle Toothbrush, launched in 1938; the first electric toothbrush, the Broxodent, followed from Switzerland in 1954.

What is the name for inflammation of the gums, the earliest stage of gum disease?

Gingivitis is gum inflammation caused by plaque along the gumline, showing as red, swollen gums that bleed when brushed; untreated it can progress to periodontitis, which destroys the bone around teeth.

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

Colgate sold aromatic toothpaste in jars from 1873 and switched to collapsible tubes in 1896; the tube idea came from dentist Washington Sheffield, who borrowed it from artists' paint tubes.

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

Crest, launched by Procter & Gamble in 1955 with Joseph Muhler's stannous fluoride formula from Indiana University, won the ADA's first seal for a fluoride toothpaste in 1960.

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?

Nitrous oxide: after seeing Gardner Colton's laughing-gas show, Wells had John Riggs pull his molar under the gas in December 1844; his Boston demonstration weeks 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?

Ratoncito Pérez, the little mouse, was invented in 1894 by the Jesuit writer 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?

The Chicago Daily Tribune: a 1908 household-hints column by Lillian Brown suggested a "tooth fairy" to coax children into having loose teeth pulled; 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?

Paul Revere, a silversmith who made false teeth on the side, recognised the ivory teeth and silver wire he had fitted for Warren; 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?

Ted Bundy's 1979 Chi Omega conviction rested partly on a bite mark on a victim matched to his teeth; the National Academy of Sciences has since concluded bite marks cannot reliably identify a person.

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

The Naval Ordnance Laboratory gave the alloy its name, NiTi-NOL; the nickel-titanium wire has shape memory, and orthodontist George Andreasen introduced it to braces in the early 1970s.

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.

What is the thin bone-like layer covering a tooth's root, where the periodontal ligament attaches, called?

Cementum is the thin, bone-like layer over the root surface into which the periodontal ligament fibres anchor, holding the tooth in its socket; unlike enamel it can be laid down throughout life.

Premolars are also known by what other name?

Bicuspids, because most premolars carry two cusps; humans have four tooth types: incisors cut, canines tear, and premolars and molars crush food.