DENTITION

•THE TEETH •THEIR FUNCTIONS•DISEASES THAT AFFECT THEM

AGE AND TEETH

DURING OUR LIVES WE HAVE TWO SETS TEETH

THE FIRST SET ARE KNOWN AS MILK TEETH

THE SECOND SET ARE KNOWN AS PERMANENT TEETH

MILK TEETH

ARE TEETH ARE SMALL AND SO ARE OUR JAWS SO THERE ARE ONLY TWENTY (20) TEETH

8 INSCISSORS 4 CANINES 8 MOLARSBETWEEN THE AGES OF 6 AND 12

THESE TEETH GRADUALLY FALL OUT, TO BE REPLACED BY PERMANENT TEETH.

TEETHING AGE OF PRIMARY TEETH

PERMANENT TEETH

AS THE MILK TEETH FALL OUT THEY ARE REPLACED BY PERMANENT TEETH. THERE ARE 32 PERMANENT TEETH

8 INCISORS 4 CANINES 8 PREMOLARS 12 MOLARS

THE LAST OF OUR PERMANENT TEETH COME THROUGH WHEN WILLWHEN WE ARE AT LEAST 18.THESE ARE CALLED OUR WISDOM TEETH

TYPES OF TEETH

AS WE KNOW THERE ARE 4 DIFFERENT TYPES OF TEETH

INCISSORS CANINES PREMOLARS MOLARS

INCISORS THESE ARE CUTTING TEETH USED FOR CUTTING

AND BITING OFF PIECES OF FOOD CHISEL- SHAPED

CANINES THESE ARE LONG AND SHARP TEETH THAT ARE USED

TO HOLD, TEAR AND PIERCING AT FOOD POINTED

PREMOLARS

THESE TEETH ARE USED TO CRUSH AND GRIND SOFT FOOD

UNEVEN CUSPS

MOLARS

THESE TEETH ARE USED FOR CHEWING AND GRINDING HARD FOOD

UNEVEN CUSPS

WHY DIFFERENT ORGANISM HAVE DIFFERENT TYPES OF TEETH? DIFFERENT SPECIES HAVE

DIFFERENT TYPES OF TEETH TO BE ABLE TO FEED ON OTHER ORGANISMS OR PLANTS

THIS IS CALLED AN ADAPTATION.

Carnivores share special adaptations for life as predators.

Large slicing canines for piercing the skin of prey, and for cutting and chewing meat

Pointed incisors for tearing flesh Even the cusps on a carnivore’s molars are

high and pointed, because these teeth too are used in tearing and chewing flesh.

Long roots on all teeth so that they are well anchored for working on the tough food material

Carnivores also have front facing eyes, heavy skulls that support the large muscles needed to work the jaws, and jaws that are very strong but that move only up and down, not from side to side.

CANIVORE

13

Canine Incisor

Incisors showing long roots

Molar

CARNIVORE TEETH

14

Herbivores feed on plant material. They need to clip green leafy material off from grass roots (grazers) and tree branches (browsers). The cellulose in leaves is ground down into a mash that can be more easily digested.

Incisors have a flat cutting edge, for use in clipping off plant stems. Since these teeth wear down from this work, there is continuous tooth growth in many species.

Canines are often lacking entirely, as the food does not need to be captured, though squirrels may have pointed incisors that look like canines, which they use to break nuts open.

Molar teeth are tall and very broad. They have flat upper jaw surfaces sometimes with ridges on them to help grind plant material.

HERBIVORES

15

Incisor Deer Molar

Molar

HERBIVORE TEETH

Insectivores have a mouthful of sharp little peg-like teeth that are similar in size and shape. These are used in seizing and

crushing hard-shelled insects, and for gripping on to worms as they are pulled from their burrows.

INSECTIVORES

17

Omnivores have the most variable teeth, used for eating both plant and animal material that make up their broad diet. Incisors are more shovel-shaped than pointed Long, sharp canines are used for puncturing and grabbing onto animal prey. Wide molar and premolar teeth handle both the chewing of meat and the grinding of plant material. They have low bumpy crowns.

incisorsmolar

premolar

canine

OMNIVORES

PARTS OF A TOOTH

FUNCTIONS OF THE PARTS OF A TOOTH ENAMEL is the hard outer shell that

covers the visible part (crown) of the tooth. It is able to withstand the stress of biting, chewing and grinding.

DENTINE is the bone-like substance that makes up most of the tooth. It is found just under the enamel in the crown and under the cementum in the root. Dentin gives the tooth its color.

FUNCTIONS OF THE PARTS OF A TOOTH CEMENTUM covers the root or roots.

cementum attaches to tiny fibers that help anchor the tooth to the jawbone.

PULP CAVITY is space containing the blood vessels, nerves and connective tissue that make up the "pulp." The pulp's blood supply provides nutrients that help to keep the tooth alive.

TOOTH DECAY

A tooth problem caused by bacteria in your mouth which mix with saliva to form plaque which is a layer which sticks to your teeth and gums.

HOW TOOTH DECAY IS CAUSED? After a meal ,sugary food may be left

between your teeth. Bacteria in plaque convert the sugar

into plaque when respiring anaerobically.

This acid attack the enamel, which is a basic substance Calcium hydroxyphosphate, thus dissolving it.

HOW TOOTH DECAY IS CAUSED? When the enamel is worn away the

enamel is worn away the acid will attack the dentine.

If the cavity reaches the pulp cavity this will be very painful and cause severe toothache.

The acid can also make your gums red and swollen.

HOW TOOTH DECAY IS CAUSED

HOW TO PREVENT TOOTH DECAY By taking in fluoride - Using fluoride toothpaste - Water supplies which contain

fluoride. Fluoride strengthens the enamel as it

reacts with the dissolving Calcium hydroxyphosphate to form an even stronger layer Fluorapatite which makes it more resistant to the acid.