My teeth are week how to make them stronger or thicker?

Weak teeth ?: Is is because of cavities or grinding? Are they chipping and breaking? If so, you need to be evaluated by a dentist to determine the cause(s) and the treatment. Once they erupt, your teeth do not "grow"... You can't make them "thicker". Make an appointment with a local dentist to be evaluated.

Weak teeth?: Broken teeth can come from many sources like grinding, eating ice, hard candy etc.And untreated decay! your problem may be easier to fix than you think ...See a dentist chuck.

Here's how....: First get them fixed with the best treatment option as advised by your dentist. Then keep them clean and healthy by brushing and flossing properly and frequently. Also eat healthy foods and avoid those that promote tooth decay. Ask your dentist about the use of Fluoride treatments and remineralizing pastes. Finally, make sure you get a dental checkup every 6 months to keep on top of things.