Hi,i want some advice about how to take care of tooth?

Watch your diet: Most importantly watch your diet and try to avoid sugary drinks. If you have a child you are worried about don't put him to sleep with a bottle in his mouth. If you are living in a community with a fluoridated water supply use it until the child is at least 12 years old. Start your kid on seeing a dentist by at least 2-3 years.

Vague Question: Not sure if you have a specific problem, but in general, brush 2x day, floss, eat a healthy diet and visit your dentist twice a year for an exam

See a Dentist: Anyone with a tooth problem should see a dentist at once for diagnosis and treatment. Hope it helps.

Tooth?: Question is vague. Can't diagnose a specific problem over computer. Important that you see a Dentist for differential diagnosis and informed treatment plan. If you are having a problem, don't wait. Dental problems do not self-cure. Get help now.