问题：

[问答题]Dental Health　　Decay is not the only disease that can cause tooth loss. Another serious disease affects the gums, the tissue that surrounds the teeth. It is also caused by bacteria. If the bacteria are not removed every day, they form a substance that stays on the teeth. The substance is known as plaque. At first, the gums appear to be swollen, and may bleed when the teeth are brushed. This can lead to serious infection of the tissue around the teeth. The infection may damage the bone that supports the teeth and cause tooth loss and other health problems. Studies have found that people with severe gum disease have an increased risk of developing heart disease, diabetes and stroke.　　Gum disease can be treated by a special dentist called a periodontist. Periodontists are trained to repair the gum areas that have been damaged. This can be painful and costly.　　Dental health experts say the best thing to do is to stop gum disease before it starts. The way to do this is to clean the teeth every day. People also should use dental floss to remove plaque from between the teeth. Most experts also agree that another way to prevent tooth and gum problems is to eat foods high in calcium and vitamins and low in sugar.　　Scientists continue to develop better dental treatments and equipment. Improved technology may change the way people receive dental treatment in the future. For example, dentists are now suing laser light to treat diseased gums and teeth. Dentists use computer technology to help them repair damaged teeth. Researchers have developed improved methods to repair bone that supports the teeth. And genetic research is expected to develop tests that will show the presence of disease causing bacteria in the mouth.　　Such increased knowledge about dental diseases and ways to prevent them has improved the health of many people. Yet problems remain in some areas. In industrial countries, minorities and other groups have a high level of untreated dental disease. In developing countries, many areas do not have even emergency care services. The World Health Organization says people in countries in Africa have the most tooth and gum problems.　　World Health Organization experts say the dental health situation is different for almost every country in the world. As a result, it has developed oral health programs separately for each area.　　The WHO oral health program is mainly for people living in poor areas. It provides them with information about mouth diseases and health care. It also studies preventive programs using fluoride in water, salt, mild and toothpaste. And it explores ways to include dental health in national health care systems.　　Many governments and other organizations provide help, so people can get needed dental health services. But dental health professionals say people should take good care of their teeth and gums.　　They say people should keep their teeth as clean as possible. They should eat foods high in calcium and fiber. These include milk products, whole grain breads and cereals, vegetables, fruits, beans and nuts. Recent studies have shown that eating nuts can help slow the production of plaque on the teeth.　　Experts say these activities will help everyone improve their dental health throughout their lives.