See MRI such things not happen daily, its used sometimes in your lifetime, so when u will do this, u can visit dentist & remove the cap, after MRI u can again put it on tooth or u can make new cap as it is least expensive, so u can go for metal, bcz it has thin structure so that it has good retention than other caps
Next Steps
if u agree than follow my above instructions
Health Tips
any doubts, u can consult me