The visible part of a tooth, otherwise known as the crown, is only a small portion of the living system. The crown is made up of enamel, the hardest substance found within the body. It is bone that has been enriched with large percentages of calcium. That's why people who drink lots of milk or take calcium supplements have strong bones and teeth. The enamel is thickest at the crown, and thinnest near the roots of the teeth. Excellent crowns and bridges were made by the Etruscans in the 7th cent. B.C. At about that time, teeth were being extracted in Asia Minor as a cure for bodily ills and diseases. Skills achieved by the Etruscans, Phoenicians, Egyptians, Greeks, and Romans were largely lost during the Middle Ages, when barbers and roving bands of charlatans practiced unskilled dentistry at marketplaces and fairs. Abulcasis, a Spanish Moor, was one of the few in his time who studied dental surgery. Dental veneers can be made from porcelain or from resin composite materials. Porcelain veneers resist stains better than resin veneers and better mimic the light reflecting properties of natural teeth. Resin veneers are thinner and require removal of less of the tooth surface before placement. You will need to discuss the best choice of veneer material for you with your dentist. Veneers, porcelain or plastic, are placed over the front teeth to change color shape of the teeth. Veneers are ideal for teeth that are too small, too big, or have uneven surfaces. It is very common for people to have imperfect teeth, either oddly shaped teeth, chipped teeth, crooked teeth, teeth with small holes in them, or an inappropriate sized tooth or teeth that have an odd appearance. Veneers solve such irregularities and create a durable and pleasing smile. While no alternative to veneers will create the exact same effect, there are some popular procedures that may seem worthwhile. Crowns, while more expensive, also act to cover the tooth with a protective coating. For individuals who simply want to brighten their teeth, many clinics now offer tooth bleaching, though this is a much less permanent procedure.
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Most women think of menopause as the time of life when their menstrual periods end. This usually occurs during middle age, when women are also experiencing other hormonal and physical changes. For this reason, menopause is sometimes called the "change of life". Perimenopause, also known as the climacteric, includes the time before menopause when hormonal and biological changes and physical symptoms begin to occur. This period lasts for an average of three to five years. Some women don't have any symptoms during menopause or only have a few symptoms. Others develop disturbing and even severe, disabling symptoms. Studies of women around the world suggest that differences in lifestyle, diet and activity may play a role in the severity and type of symptoms women have during menopause. Symptoms can be noticed for several months to years before the last menstrual period and can continue for several years after. As estrogen levels drop and remain low during menopause, the risk of developing osteoporosis increases. The risk is greatest for slender, white or light-skinned women. You can help prevent osteoporosis by getting enough vitamin D through sunlight or a daily multivitamin, eating a diet rich in calcium and performing regular exercise. Women should start taking these actions well before menopause begins. This is because women begin to lose bone mass as early as age 30 but fractures resulting from osteoporosis don't occur until 10 to 15 years after menopause. Before menopause, women have lower rates of heart attack and stroke than men. After menopause, however, the rate of heart disease in women continues to rise and equals that of men after age 65. Menopause is a natural event and cannot be prevented. Medications, diet and exercise can prevent or eliminate some symptoms of menopause and enhance a woman's quality of life as she grows older.
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Skin has pigmentation, provided by melanocytes, which absorbs some of the potentially dangerous radiation in sunlight. It also contains DNA repair enzymes which reverse UV damage, and people who lack the genes for these enzymes suffer high rates of skin cancer. One form predominantly produced by UV light, malignant melanoma, is particularly invasive, causing it to spread quickly, and can often be deadly. Human skin pigmentation varies among populations in a striking manner. This has sometimes led to the classification of people on the basis of skin color. See the article on human skin color. The skin is often known as "the largest organ in the human body". This applies to exterior surface, as it covers the body, appearing to have the largest surface area of all the organs. Moreover, it applies to weight, as it weighs more than any single internal organ, accounting for about 15 percent of body weight. For the average adult human, the skin has a surface area of between 1.5-2.0 square metres, most of it is between 2-3 mm thick. The average square inch of skin holds 650 sweat glands, 20 blood vessels, 1000 melanocytes, and more than a thousand nerve endings. The dermis lies below the epidermis and contains a number of structures including blood vessels, nerves, hair follicles, smooth muscle, glands and lymphatic tissue. It consists of loose connective tissue otherwise called areolar connective tissue - collagen, elastin and reticular fibres are present. Erector muscles, attached between the hair papilla and epidermis, can contract, resulting in the hair fibre pulled upright and consequentially goose bumps. The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves. It consists of loose connective tissue and elastin. The main cell types are fibroblasts, macrophages and adipocytes (the hypodermis contains 50% of body fat). Fat serves as padding and insulation for the body. The constantly peeling off dead cells of the epidermis mix with the secretions of the sweat and sebaceous glands and the dust found on the skin to form a filthy layer on its surface. If not washed away the dirt and dead skin slurry begins to decompose emitting a foul smell.
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