The biological structures that are so versatile they enable us to eat a varied diet!
The primary function of teeth is to crunch and chew food. For this reason, teeth are made of strong substances -namely calcium, phosphorus and various mineral salts. The main structure of the tooth is dentine, this itself is enclosed in a shiny substance called enamel. This strong white coating is the hardest material found in the human body.
Humans have different types of teeth that function in various ways. Incisors tear at food, such as the residue found on bones, while bicuspids have long sharp structures that are also used for ripping. Bicuspids tear and crush while molars, which have a flatter surface, grind the food before swallowing. This aids digestion. Because humans have a varied array of teeth (called collective dentition) we are able to eat a complex diet of both meat and vegetables. Other species, such as grazing animals, have specific types of teeth. Cows, for example, have large flat teeth, which restricts them to a simple diet.
Teeth have many functions, in some cases they aid hunting but they also have strong psychological connotations. Both animals and humans bare their teeth when faced with an aggressive situation. Teeth are the most enduring features of the human body. Mammals are described as diphyodont, which means they develop two sets of teeth. In humans the teeth first appear at six months old and are replaced by secondary teeth after six or seven years. Some animals develop only one set of teeth, while sharks, for instance, grow a new set of teeth every two weeks.
From ancient times healers have sought to treat and replace the teeth with false ones. Examples of this practice can be seen from ancient Egyptian times and today, we see revolutionary new techniques in the form of dental implants, which are secured deep within the bone of the jaw.
The trouble with teeth
Tooth decay, also often known as dental caries, affects the enamel and dentine of a tooth, breaking down tissue and creating fissures in the enamel. Two types of bacteria – namely Streptococcus mutans and Lactobacillus-are responsible for tooth decay.
Tooth decay occurs after repeated contact with acid-producing bacteria. Environmental factors also have a strong effect on dental health. Sucrose, fructose and glucose create large problems within the mouth, and diet can be an important factor in maintaining good oral health.
The mouth contains an enormous variety of bacteria, which collects around the teeth and gums. This is visible in the form of a sticky white substance called plaque. Plaque is known as a biofilm. After eating, the bacteria in the mouth metabolizes sugar, which subsequently attacks the areas around the teeth.
Medication can also affect oral health, reducing the production of saliva, which offers natural protection and works against acidic matter. Various treatments can be applied to teeth that are damaged or decayed, these include extraction, filling or the replacement of teeth in the form of either dentures and implants.
The tooth is a complex structure. The enamel at the surface of the tooth is highly visible while the dentine is a hard but porous tissue found under the enamel. The gums provide a secure hold for the tooth, while the root is anchored right into the jawbone. In the centre of the tooth there is a substance called pulp which contains nerves and blood vessels, the pulp nourishes the dentine and keeps the tooth healthy.
Tooth formation begins before birth. Normally there are 20 primary teeth (human baby teeth) and later, 28 to 32 permanent teeth, which includes the wisdom teeth. Of the primary teeth, ten are found in the maxilla (the upper jaw) and ten in the mandible (lower jaw), while the mature adult has 16 permanent teeth in the maxilla and 16 in the mandible.
Animal teeth facts
1. A hippopotamus has an enormous mouth that can measure up to 1.2 metres wide. They are equipped with a pair of huge and very dangerous incisors.
2. Piranha teeth are very small but can be extremely sharp and are often used by the local populations of South America to create a variety of tools and weapons.
3. A member of the rodent family, the hamster has teeth that grow continuously. They therefore need to grind their teeth on a hard substance to prevent overgrowth.