IDK. If your dentist was 'unsure' about whether or not you had bone resorption around the root canaled tooth, I don't think you can expect non-dentists on here to be more sure as to tell you what to do.
You say the root canal was done to the 'wisdom tooth'. The X ray of the root canal is to tooth #31. #31 is a SECOND MOLAR and NOT a wisdom tooth.
So, if you don't know the difference between a wisdom tooth and a second pre-molar, try not to freak yourself out as to what you think an X ray is conveying especially in light that the dentist told you it needs no further treatment.