Bad teeth can be painful and even be deadly. Infections of the gums (牙龈) and teeth can release bacteria into the blood system. Those bacteria can increase the chance of a heart attack or stroke and worsen the effects of other diseases. And adults are not the only ones at risk. For example, a 12­-year-­old   boy died when a tooth infection spread to his brain in 2007 in Washington. Experts said it might have been prevented had he received the dental care he needed.

Experts say good dental care starts at birth. Breast milk，they say，is the best food for the healthy development of teeth. Breast milk can help slow bacterial growth and acid production in the mouth. But dentists say a baby’s gums and early teeth should be cleaned after each feeding by using a cloth with a little warm water. Experts say if you decide to put your baby to sleep with a bottle, give only water.

When baby teeth begin to appear，you can clean them with a wet toothbrush. Dentists say it is important to find soft toothbrushes made especially for babies and to use them very gently. The use of fluoride (氟化物) to protect teeth is common in many parts of the world. For example, it is often added to drinking water supplies. The fluoride mixes with enamel (釉质)，the hard surface on teeth, to help prevent holes from forming.

But young children often swallow toothpaste when they brush their teeth. The American Academy of Pediatric Dentistry notes that swallowing fluoridated toothpaste can cause problems. So young children should be carefully watched when they brush their teeth. And only a small amount of fluoridated toothpaste, the size of a pea, should be used.

Parents often wonder what effect finger sucking might have on their baby’s teeth. Dental experts generally agree that this is fine early in life. Most children stop sucking their fingers by the age of four. If it continues，experts advise parents to talk to their children’s dentists or doctors because it could interfere with the correct development of permanent teeth.

Dentists say children should have their first dental visit at least by the time they are one year old. They say babies should be examined when their first teeth appear—usually at around six months.

Why do men die earlier than women? The latest research makes it known that the reason could be that men's hearts go into rapid decline when they reach middle age.

The largest study of the effects of ageing on the heart has found that women's longevity may be linked to the fact that their hearts do not lose their pumping power with age.

"We have found that the power of the male heart falls by 20--25 percent between 18 and 70 years of age,”said the head of the study, David Goldspink of Liverpool John Moores University in the UK.

"Within the heart there are millions of cells that enable it to beat. Between the age of 20 and 70，one-third of those cells die and are not replaced in men,”said Goldspink. "This is part of the ageing process."

What surprises scientists is that the female heart sees very little loss of these cells. A healthy 70-year-old woman's heart could perform almost as well as a 20-year-old one's.

"This gender difference might just explain why women live longer than men,”said Goldspink.

They studied more than 250 healthy men and women between the ages of 18 and 80，focusing on healthy persons to remove the confusing influence of disease.

The team has yet to find why ageing takes a greater loss on the male heart, said Goldspink.

The good news is that men can improve the health of their heart with regular exercise. Goldspink stressed that women also need regular exercise to prevent their leg muscles becoming smaller and weaker as they age.

Crossing your legs is an extremely common habit; most people don’t even notice that they’re doing it when they sit down. While you may find it comfortable to sit with one knee crossed over the other, it might be causing health problems that you are not aware of.

A study published in Blood Pressure Monitoring stated that sitting with your legs crossed can increase your blood pressure. The reason this happens is because the blood in your legs has to work against gravity to be pumped back to your heart, crossing one leg over the other increases resistance, making it even harder for the blood to circulate. This causes your body to increase your blood pressure to push the blood back to the heart. You won’t feel any immediate effects, but if you sit for long periods of time it’s important that you take note of how long you have your legs crossed for. You shouldn’t have your legs crossed for more than 15 minutes, and it’s important that you get up and walk around at least once every hour.

Crossing your legs can also lead to neck and back pain. Ideally, it’s best for our bodies to sit with our feet planted flat, hip width apart, on the floor, but it’s not easy to maintain perfect posture all day at the office. When you sit with your legs crossed your hips are in a twisted position, which can cause one of your pelvic bones to rotate. Since your pelvic bone supports your neck and spine, this can cause pressure on your lower and middle back and neck.

You also might notice that when you sit with your legs crossed for long periods of time your feet and legs get tingly or have the feeling of being asleep. This is because when one leg sits on top of the other it causes pressure on the veins and nerves in your legs and feet. It can cause numbness and/or temporary paralysis in the legs, ankles, or feet. While the feeling of discomfort may only last a minute or two, repeatedly crossing your legs until they feel numb can cause permanent nerve damage.

So next time you sit down, try to get yourself in the habit of sitting with both of your feet on the floor. Not only will it help your posture and stability, but it will also save your health in the long run.