Answer: Cats don’t chew their food as we do. The natural function of their teeth is to serve as a means of killing of their prey and of cutting it up into pieces small enough to swallow.
The large canine teeth (‘fangs’) are use to kill the prey by a bite to the neck with the two opposing teeth on the top and bottom jaw, penetrating on of the joints between the victims’s neck vertebrae to sever the spinal cord. Then the premolar and molar teeth along the sides of the jaw are used to cut up the prey into pieces or strips which can be swallowed. Especially important are the largest of the teeth (the carnassials) which have a scissor like action as the jaws close. The small incisor teeth at the front of the jaws can be used for pulling flesh off bones as well as for carrying objects, e.g. prey and kittens.
Cats fed on conned or home cooked diets, or even raw meat which has been well cut up into tiny pieces, have no need to use their teeth at all. As result of this lack of ware, tartar accumulates on the teeth initiating a dental disorder which may end the teeth loosing and dropping out, or having to be removed. But of course if the cat needs only to swallow the same precooked, soft food, it will certainly not require its teeth, and indeed there are many old cats who have los all their teeth and yet eat normally and remain quiet healthy. So the presence of teeth is not essential and digestion will proceed normally with or without them, although of course a cat with out teeth is not so well placed to defend itself.
Obviously, it is preferable to prevent the cat from losing its teeth. This may be achieved by feeding it chunks of whole meat to tear at or dry foods, or by giving some large, hard biscuits or a hide chew (available at pet shops in various shapes). All of these will provide good dental exercise and reduce the possibility of dental disorders developing later.
