Now that the tooth is decayed you have seravel options1. Crown Lengthening and crown; Since there the body (coronal portion)of the tooth is gone. You can have a procedure done to actually remove bone to expose healthy root structure(usually no more than 2mm). this procedure allows the dentist finish a crown on the health tooth structure. This procedure is destructive to bone but is usually chosen by the patient who is not ready to loose a natural tooth. 2. Bridge; You can have the tooth removed and have a bridge placed. This is an option provided that it is not the last tooth in the arch. so there has to be a tooth in the front and the back, to allow the bridge to be placed. 3. You can have tooth removed and have an implant placed. This is by far the most expensive in the short term but has the potential to cost you less in the long-term since implants don’t decay. The only risk is of structural failure and bone infection (low with reasonable care). this is a great option. However prices can skyrocket if you need a bone graft. Since you had the root canal a couple of years ago chances are the bone is still pretty good in your case.4. You can have the tooth removed and have a flipper made. The is a plastic partial denture, made to fill the space. This is an option if funds are limited and you need the gap filled for aesthetic purposes. 5. You can have a removable permanent denture made. This is similar to the flipper, but the design is different. It has metal bars and lots of spaced to allow the tissues to breath thus allowing it to be used long-term without harming the gums. Prices range from $350 for a flipper, to $3500 for implant and crown. good luck