Q. hi andrew, i had root canal treatment and and crown replacement which has led to what was described as a facial nerve being danaged over 7 months ago a consultant along with another dentist has indicated that either part of the root canal treatment has been left inserted in my gum or its part of an instrument as yet they are not quite sure but may require micro surgery to remove in addition to this during a treatment session the wrong crown was pulled from my upper front left side casing trauma and severe facial sewlling to date this swelling is still evident and severe pain is constant as a result of poor treatment. can you advise. thanks,