In daily outpatient clinics, patients often present with toothache as the chief complaint, but the doctor does not find the affected tooth corresponding to the symptoms of toothache during the examination. When the doctor tells the patient that the tooth is not the cause of the pain, it is often difficult for the patient to understand. In fact, lesions of organs adjacent to the teeth can also cause similar symptoms of toothache, such as maxillary sinusitis, sinusitis, jaw tumors, trigeminal neuralgia, etc. It has been reported that 18% of patients with coronary artery disease have toothache, which is easily misdiagnosed and mistreated if not differentiated, and may be life-threatening. The following is the treatment history of a patient seen in our department: The patient was female, 36 years old. She was diagnosed with periapical periodontitis and periodontitis in the lower anterior teeth and underwent endodontic treatment, but her symptoms did not improve, so she came to our hospital. The examination showed that the lower anterior tooth lingual cotton twist open, percussion pain (+), loosening III ° can be explored periodontal pocket near the tip of the root, lip side gingival expansion, size of about 1 × 1cm2 , surface mucosa white, hard, pressure pain (+), X-ray film shows: lower anterior tooth apical large hypodensity image. A surface tomography was taken, showing irregular hypodense images of bone tissue in the mandibular body and destruction of the bone cortex at the mandibular margin. It was suspected to be a malignant tumor of the mandible and was referred to surgery for further treatment. The biopsy pathology was diagnosed as osteosarcoma, and expanded resection of mandibular spindle cell sarcoma + left submaxillary triangle clearance + left fibula free graft repair + titanium plate implantation + pneumonectomy was performed.