Hello, generally, teeth that have undergone root canal treatment need braces to be repaired, on the one hand, to protect teeth from cracking, on the other hand, to achieve the purpose of beauty. Because of root canal therapy, the crown will become gray and brittle, which is not only unsightly, but also easy to crack when biting hard things. Suggestion: actually, this is the case. After root canal therapy, crown restoration is generally needed, which can be used as normal teeth, usually for two to three years, and good ones can be used for decades. On the one hand, it depends on the condition of the root, on the other hand, it depends on the material.