Fractured Tooth while removing crown.

I have been experiencing an occassional tooth sensitivity in my RCT tooth since last 2 months but it became severe since few weeks during which I was unable to even chew food from that side. I visited a dentist and the doctor suggested that the artificial crown which was fixed after RCT needs to be removed as a gap has been observed between the teeth in X-ray. The doctor further suggested, there is a decay in my original RCT tooth which is leading to sensitivity.After removal of crown,then only it can be decided whether a filling & crowning can do or a re-RCT and crowning needs to be done. But while removal of the crown, they told me that there is a fracture in my tooth. The fracture was not there before crown removal, it occurred while crown removal, which they have admitted.What they have suggested me now is extraction of my tooth and tooth implant which is an expensive treatment. Could you please suggest is there any treatment by which I can avoid the tooth extraction.