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Teeth are invaluable to everyone. They enable you to cut and grind the morsel of food, which is moistened by saliva. Biting the food makes it small enough to pass down the gullet into the stomach. Digestion is made easier if these pieces of food are crushed into even smaller particles by the action of chewing. You will have heard grown ups tell children to "chew the food properly", as this makes easier for the stomach to digest the food. In a lifetime, we are given only two sets of teeth. At birth, a human baby has no teeth, but normally after six months the first teeth appear in the centre of the lower jaw. By the time the infant is two years old, he is the proud owner of a set of 20 teeth called "milk teeth". There are ten in each jaw. At the age of six or seven years, these teeth begin to fall out and are replaced with a permanent set of teeth. In addition, three more teeth, the molars, erupt on each side in the back part of the jaw. The permanent set consists of 32 teeth among them and the four "wisdom teeth" which are located at the back of each jaw. These wisdom teeth usually erupt during the late teens. Teeth are given different names according to their position in the jaw. The 32 teeth include four incisors (these help to cut food); two cuspids or canines (tear food); four bicuspids (tear and crush food); and six molars (grind food) in each jaw. Incisors, or the front teeth help cut pieces off the food, as when biting into an apple or taking a bite out of a sandwich. Canines are located on each side of the incisors. They are a little pointed they function as extra incisors. Bicuspids are also known as premolars. The premolars and molars are similar in function. Their knobbly surfaces meet when the jaws are closed, and crush the food into small pieces. As well as breaking the food into a suitable size for swallowing, the crushing action of the molars and premolars reduces food to quite small particles. Small particles of food are easier than large pieces because they offer a greater surface area to the digestive enzymes. The structure of the tooth is as follows: the outer layer of the tooth has a "skin" of enamel. Enamel covers the exposed part, or crown of the tooth and makes a hard biting surface. It is mainly calcium phosphate, the hardest mineral substance in the body. Since the enamel contains no nerves, it is insensitive to pain. Under the enamel comes the dentine, which is related to the bone. Dentine is softer than enamel. It is a living tissue with threads of cytoplasm running through it. Tooth sensitivity begins here. The hardness of both enamel and dentine depends on there being enough calcium in the diet and sufficient vitamin D to help the absorption of calcium in the intestine. Beneath the dentine lies the pulp, a relatively soft material containing nerves, blood vessels and cells that radiate into the dentine. These blood vessels bring food and oxygen, so that the tooth can grow at first and then remain alive when growth has stopped. The sensory nerve endings in the pulp are sensitive to heat and cold but give only the sensation of pain. If you plunge your teeth into an ice-cream, they do not feel cold but they do hurt. The reason why teeth do not fall out easily is because they are anchored by "cementum". This cement is a bone like tissue which covers the root of the tooth. In the cement are embedded thousands of tough fibres which pass into the bone of the jaw and hold the tooth in place. Did you know that the most common disease in the world is tooth decay? Careful brushing and careful cleaning between teeth is essential. The most likely reasons for the loss of teeth are dental decay and gum disease. Dental decay (dental caries) Decay begins when small holes or cavities appear in the enamel. The cavities are caused by bacteria on the tooth surface. The bacteria produce acids which dissolve the calcium salts in the tooth enamel. The enamel and dentine are dissolved away in patches, forming cavities. The cavities reduce the distance between the outside of the tooth and the nerve endings. The acids produced by the bacteria irritate the nerve endings and cause toothache. If the cavity is not cleaned and filled by a dentist, the bacteria will get into the pulp cavity and cause a painful abscess at the root. Often the only way to treat this is to have the tooth pulled out. Although some people's teeth are more resistant to decay than others, it seems that it is the presence of refined sugar (sucrose) that contributes to decay. Western diets contain a good deal of refined sugar and children suck sweets between one meal and the next. The high level of dental decay in Western society is thought to be caused mainly by the prolonged presence of sugar in the mouth. The best way to prevent to prevent tooth decay, therefore, is to avoid eating sugar at frequent intervals either in the form of sweets or in sweet drinks such as orange squash or Coca Cola. It is often stated that eating hard fibrous food, such as raw vegetables, removes plaque and prevents decay but there is not much evidence to support this. Brushing the teeth or rinsing the mouth does little to prevent dental decay. However, if a fluoride toothpaste is used to it does help to increase the resistance of enamel to bacterial acids. Adding fluoride to drinking water also reduces the incidence of dental decay but it is a controversial measure. Brushing the teeth is very important in the prevention of gum diseases, which causes more tooth loss than caries does. Gum Disease (periodontal disease) There is usually a layer of saliva and mucus over the teeth. This layer contains bacteria which live on the food residue in the mouth, building up a coating on the teeth, called plaque. If the plaque is not removed, mineral salts of calcium and magnesium are deposited in it, forming a hard layer of 'tartar' or calculus. If the bacterial plaque which forms on teeth is not removed regularly, it spreads down the tooth into the narrow gap between the gum and enamel. Here it causes inflammation, called gingivitis, which leads to redness and bleeding of the gums and to bad breath. It also causes the gums to recede and expose the cement. If gingivitis is not treated, it progresses to periodontitis. The fibres holding the tooth in the jaw are destroyed, so the tooth becomes loose and falls out or has to be pulled out. There is evidence that cleaning the teeth does help to prevent gum disease. It is best to clean the teeth about twice a day using a toothbrush. No one method of cleaning has proved to be any better than any other but the cleaning should attempt to remove all the plaque from the narrow crevice between the gums and the teeth. Drawing a waxed thread or dental floss between the teeth helps to remove plaque in these regions. So! Take care of your teeth and remember to visit your dentist regularly!
Article Source: http://www.healthfreakarticles.com
Rosie Shaw runs her Free Recipes website and Cooking Tips and techniques site www.Cook-It-All.com. You can also find Free Health and Fitness Articles at Cook It All.com
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