You will almost always have more than one option. You may want a removable partial denture, or a fixed partial denture. Your options will be based on dollars you can spend and what you want removable or fixed and condition of soft and hard tissue good luck
Kevin Coughlin DMD, MBA, MAGD CEO Baystate Dental PC
Failing root canal options
This depends on the stability of the tooth and the remaining tooth structure. If both are good then you could see an endodontist (root canal specialist) and ask them about doing a re-treatment to eliminate the infection. If it is a front tooth and the tooth structure is intact, then you could try doing an internal bleach after the root canal re-treatment is done. If not then do a porcelain crown.
It the tooth stability is not good or the structure is compromised, then consider the implant.
I would definitely consult with an endodontist ( a root-canal specialist) and a restorative dentist on the pros and cons of trying to save this tooth. There are many things than can be done to save a tooth such as root canal retreatment, apicoectomy, and crown lengthening in addition to having a new crown made, but only a doctor doing a complete exam on this tooth can give you more definitive options.
They can try internal bleaching with superoxol - high content peroxide. That can take the brown out. If there is no infection, you could also just crown the tooth to match the others. It would be helpful to have a picture and x-rays to give you a better opinion. I would suggest you go for a couple more opinions.