For RCT this tooth prognosis is poor due to huge lesion/infection under the root region and also look like broken file in the apical third region

Thank you for sharing your OPG. On the radiograph, the capped tooth appears to have a significant infection around the root (periapical area). When a previously treated tooth shows such changes, the long-term prognosis depends on factors like remaining tooth structure, bone support, and whether retreatment can adequately eliminate the infection. In some cases, a re-root canal (retreatment) may be attempted to save the tooth. However, if the infection is extensive or the tooth is structurally weak, extraction followed by replacement (such as an implant or bridge) can provide a more predictable outcome. An OPG gives a general overview, but the final decision requires clinical examination, symptoms, and sometimes a small intra-oral X-ray or CBCT. I would recommend getting it evaluated in person so the tooth can be assessed for save vs replace in a predictable and safe manner. If you want, you may share: • whether you currently have pain/swelling • when the RCT/crown was done • any history of repeated infection I can then guide you more specifically about the best option.

Implant maybe an option in the future but due to big carious lesion currently it will be an option in few months 

According to your xray, there is huge infection beneath the root of the tooth, and probably a file separation is also seen. Prognosis of the tooth is not very good. It is better to go for replacement of the teeth

From the OPG image, there appears to be significant damage around the capped tooth, likely involving the root or surrounding bone. If there is: • Large infection at the root tip • Severe bone loss • Root fracture Then extraction and implant may be the more predictable option. If the root structure is intact and bone support is adequate, retreatment with RCT and a new crown can sometimes save the tooth. An OPG alone is not always sufficient for final decision. A clinical exam and possibly an IOPA or CBCT give better clarity. If long-term prognosis is doubtful, implant is more reliable. If the tooth is structurally sound, saving it is always preferred.

In case of moderate prognosis for particular tooth, implant can be preferred

Hello The capped tooth shows infection,better to get it extracted and get an implant done

Hello From the OPG x-ray seems like there is tooth infection You need extraction because root canal treatment will not help it