Cats don't chew their food as human does. Their teeth serve as a device for killing prey and tearing into pieces, small enough to swallow.
When it kills prey a cat uses its' big fangs situated on the upper and lower jaws. Fangs penetrate between neck vertebrae and tear the backbone. To tear a prey on pieces or stripes that are swallowed then a cat used major and minor molars of both jaws. The largest teeth that move scissors-like when jaws close up are of special importance. Small front incisors serve to separate meat from bones and to carry different things, prey or kittens, for example. It's clear that all teeth and especially fangs are used for defense and attack.
Cats fed with canned goods, kitchen food and even fresh meet cut in small pieces don't need teeth at all. Tooth stones accumulate on standing surfaces that are the reason of diseases, and in result teeth become loosen and come out or are needed extraction. Many old cats stay without teeth but continue eat well and feel themselves quite good. Thus the presence of teeth is not obligatory - food absorption goes normally both with them and without them, yet a toothless cat is deprived from its' gun of self-defense.
It's obvious, that it'd be better to preserve teeth in cats. One may promote this by feeding his cat with big pieces of meat that cat might gnaw, and with dry food. All this represents a perfect exercise for teeth and reduces the probability of tooth diseases.
Translated by Tatiana Karpova (Moscow)
(MSU, Biology faculture, Dep. zoology and ecology).