Patient: Dr. Duan Hello. I had my nerve extracted last week and the doctor said I should have a filling this week and a crown restoration next week. Is there any effect on the crown restoration if I do it after a while? Or is the best time to have a crown restoration when the tooth has just been filled? 2. Will the tooth loosen if the nerve is extracted? Or, if the tooth is broken later, will it loosen only after it is extracted? (I have the second last tooth below) 3. （The doctor said that some of them will cause the flesh of the tooth to become black, but my tooth is inside, so I don’t have to worry about that. Why would braces cause the flesh of the teeth to turn black? Duan Jin, Department of Stomatology, Huzhou Central Hospital: 1. The purpose of doing the crown is to prevent the tooth without nerve (like a dead tree, it will become brittle) splitting, the probability of the back teeth some foreign information said nearly 50%. You do it later, then the time to take the risk will be extended. Oh, but there are also the disadvantages of doing a crown (chipped porcelain, grinding teeth, etc.). The lesser of two evils. 2, the nerve extraction of the tooth is like a dead tree, as long as the root of the soil is still there, the tree will not fall. If the tooth is healthy, the tooth will not loosen. In addition, in general, the loosening of the neighboring teeth is negligible after the extraction of the tooth. However, it is possible that the neighboring teeth may fall into the gap, just possibly. 3, there are many materials for dental crowns, just like eating on the street, there are roadside stalls, there are KFC, and even HOTEL. depending on their own economic ability, generally speaking, expensive is not necessarily good, but the good must not be cheap. The reason for the blackening is: the cheap kind of porcelain teeth inside the metal is nickel-chromium alloy, nickel is not stable, can be free, deposited on the gums, making the edge of the crown black. If the economy is generous, or do not do the nickel-cadmium porcelain teeth.