Crowns are strong and generally last for about 10 years or longer if you take good care of them. Brush and floss your crown, just like you clean your natural teeth. After flossing, roll it up in a tiny ball and put it in the garbage. Never flush floss down the toilet. Crowns may not be as strong as your natural teeth. So like your natural teeth, remember not to bite down on hard objects or use your teeth to open or cut things.