The prefix bi meaning two. The first upper premolars normally have two roots. The other premolars have one root. These are larger than premolars and extremely variable depending on the animal's diet. Like premolars they are used for crushing and grinding food, and like premolars their upper surfaces have ridges called cusps on them.
Molars normally have three to five cusps and two or three roots.
In humans we call the third molars, those closest to the back of the mouth 'Wisdom Teeth'. If the jaw bone is not large enough to accommodate all the teeth in it, as sometimes happens with humans, these wisdom teeth can become painfully wedged between the back of the jaw bone and the 2nd molars. This condition is known as 'impacted wisdom teeth'. These pages are here free for you to use, I would like to keep them that way, however making and running this site, and the other sites I am currently making or have made, on Birds, Mammals, Insects and Fish and Bacteria costs money. There are simple ways you can help.