Tooth
Teeth were part of the anatomy of most species. Their shape varied from the flat and short teeth of species such as humans, to the pointy teeth of species like the Futurekind, to the long, sharp teeth of species like Multi-forms. The humans of Silo 16 used this anatomical difference to differentiate between human and Futurekind. (TV: Utopia, The Eleventh Hour) Sharp teeth left "tooth marks". (TV: Mindwarp)
To find out what a life form ate someone had to look at its teeth. Canine teeth were used for spearing and ripping through meat. Incisors were used for cutting up food. Molars were used for grinding up food. Pre-molars were used for chewing food. The Judoon had got canines, incisors, molars and pre-molars - the teeth of an omnivore, which meant they ate meat and vegetables. (WC: Teeth and Eating)
Upon his regeneration, the first thing the Tenth Doctor remarked on was his new teeth — "That's weird". (TV: The Parting of the Ways) River Song also remarked on her teeth immediately after one of her regenerations. (TV: Let's Kill Hitler)
Too much sugar could damage teeth; the Tenth Doctor didn't allow himself the rest of his Easter egg in favour of "keeping these teeth". (TV: Planet of the Dead) According to Jack Harkness, Brits had bad teeth. (TV: Greeks Bearing Gifts) Toothbrushes were used to clean them. (TV: Mutant Copper) According to the Eleventh Doctor, food tasted weird after cleaning one's teeth. (TV: The Eleventh Hour) Gallifreyan physiology did not allow for tooth decay, but the Tenth Doctor liked to brush his anyway. (PROSE: Keeping up with the Joneses)
Dentists took care of or healed people's teeth; when the First Doctor had a toothache, he had to seek dentist Doc Holliday to fix it in Tombstone, Arizona in October 1881. (TV: The Gunfighters)
George Washington had wooden teeth. (AUDIO: The Mahogany Murderers)
Max Capricorn had a gold tooth which, both in real life and in his advertisements, glinted when he said, "My name is Max." (TV: Voyage of the Damned)
References
"Hell's teeth" was an exclamation. (TV: Logopolis)
The expression "baring one's teeth" alluded to, in the words of the Eleventh Doctor, "talking up war", as both sides of the Cold War were doing. (TV: Cold War)
Queen Katryca's right hand man was named Broken Tooth. (TV: The Mysterious Planet)
