Complications Allergic reaction to the anesthetic Toxicity due to anesthetic overdose (eg, seizure, cardiac arrhythmias) Intravascular injection of anesthetic / epinephrine Hematoma Neuropathy Spread of infection, by passing the needle through an infected area Anesthetization of branches of facial nerve (cranial nerve VII) due to excessively posterior needle placement Failure to anesthetize Needle breakage and loss of needle within soft tissues Most complications result from inaccurate needle placement.