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VARIATIONS IN TEETH

First broadcast on www.provet.co.uk  


This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Many different species of animal have teeth, but they vary in number, shape and anatomy depending upon the type of food that the animal eats, and other factors.

Teeth are usually white or yellow-white and are found on both the upper and lower jaws. They are used for :

  • Obtaining food - called "prehension"
  • Chewing food - called "mastication"
  • Weapons

Humans and domesticated animals have two different sets of teeth. The first set (called temporary, milk or deciduous teeth)  are replaced during the growing stage of life by the second set (called permanent teeth). Problems can occur during the change-over period. For example, in toy breeds of dog (eg Yorkshire Terriers) the temporary teeth sometimes do not fall out when they should so the dog has two rows of teeth and veterinary dental attention may be needed ! 

There are 4 different types of teeth based upon their anatomical shape and position in the mouth:

  1. Incisors - these are located at the front of the mouth
  2. Canine teeth - these are found behind the incisor teeth
  3. Premolars - lie behind the canines and in front of the molars
  4. Molars

The number of each type of tooth varies from one species to another and the conventional way of describing them is by a "dental formula". The type of teeth are indicated by the first letter, and the number of teeth on one side of the upper jaw is indicated over the number of the same type of teeth on the lower jaw. Because the formula is for one side of the mouth the total number of teeth is the total in the formula x 2.

Man (adult)

I - 2/2   C - 1/1   P - 2/2   M - 3/3 = 16 x 2 = 32

.CLICK HERE for the dental formula of different species

The teeth are numbered starting from the midline of the front of the jaw...so the 1st incisor is positioned at the front of the jaw next to the midline and the 2nd incisor lies behind it and so on.

The teeth have different functions :

  • Incisors - are mainly concerned with prehension (see above) 
  • Canines - are mainly concerned with prehension and as weapons. Well developed canines are called "fangs" - eg big cats, or "tusks" eg walrus, hippos, elephant.
  • Premolars and molars are used for chewing and grinding food (mastication) 

Ruminants (cattle, sheep goats) have evolved without canine teeth because they eat plant material, they do not have to catch prey and they are placid herding creatures.

Dogs and cats on the other hand have well developed canines reflecting their natural food in the wild - live prey.

Teeth are extremely strong and are made up of a variety of materials. The outer exposed shell (called the crown) consists of enamel which is the hardest material in the body, and below the gum lies the root which is attached to the underlying bony socket in the jaw. Nerves and blood vessels supply the tissue in the middle part of the tooth - called the pulp. This is the part of the tooth which is sensitive to pain if the tooth is damaged or gets infected. In some species the teeth wear down with use, and older animals the pulp cavity can become exposed...causing discomfort.

The shape and size of teeth varies between species . Cats and dogs have one very large cheek tooth - called the "carnasial" tooth - and they use this to gnaw at bones to remove the muscle and other soft tissues,  whereas in horses and ruminants the crowns of the cheek teeth are all much the same in shape and size as they are used to grind plant material.

In many species ( but not man, dogs or cats) the teeth can continue to grow for a considerable period of the animal's lifetime. This is especially true of rodents (mice, rats), cavies (guinea pigs)  and lagomorphs (rabbits) in which they can continue to grow throughout life. In these species the two large incisors at the front of the mouth  rely on contact with teeth on the opposite jaw to wear them down and keep them the correct length. If for some reason the teeth do not meet properly they will become very long, and grow in a curve - eventually stopping the animal from eating.

 

Updated October 2013