How many teeth are in a full adult set, including wisdom teeth?
Answer32
A full adult set has 32 teeth, including four wisdom teeth.
Health · Facts & stats
Smile facts & stats
7 fact-checked facts about smiles and teeth, each with the reason behind it. 5 more are in today's round and join this page after it closes.
The basics
What is the hardest substance in the human body?
AnswerTooth enamel
Enamel, the outer layer of teeth, is the hardest and most mineralized tissue in the body.
Going deeper
A genuine smile that crinkles the eyes is named after which French scientist?
AnswerGuillaume Duchenne
Duchenne studied facial muscles in the 1800s; a smile that engages the eyes is called a Duchenne smile.
In which decade was the classic yellow smiley face designed by Harvey Ball?
Answer1960s
American artist Harvey Ball drew the yellow smiley face in 1963 for an insurance company's morale campaign.
Which layer of a tooth lies directly beneath the enamel?
AnswerDentin
Dentin is the yellowish layer under the enamel; the soft pulp with nerves sits inside it.
Expert level
Which muscle around the eye tightens in a genuine smile that crinkles the eyes?
AnswerOrbicularis oculi
The orbicularis oculi circles the eye; its contraction creates the crow's-feet crinkles of a genuine smile.
Tooth enamel is made mostly of which mineral?
AnswerHydroxyapatite
Enamel is about 96% mineral, mostly hydroxyapatite, a crystalline calcium phosphate.
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