Pneumomediastinum and subcutaneous emphysema occur due to the presence of free air in the mediastinum and subcutaneous tissue. Early diagnosis and therapy are crucial as the passage of huge amounts of air into the mediastinum may lead to lethal complications. We report a rare case of cervical subcutaneous emphysema and pneumomediastinum occurring after extraction of the mandibular left first molar using an air-turbine drill. A 54-year-old woman presented to the emergency service with the complaints of left cheek and neck swelling and dysphagia. Her symptoms began following a dental surgery—the extraction of the mandibular left first molar. Computed tomography showed subcutaneous emphysema, which extended bilaterally from the left cervico-facial region to the anterior and posterior mediastinum. She was admitted to our service for follow-up and antibiotic treatment with a diagnosis of subcutaneous emphysema and pneumomediastinum due to dental extraction. Five days later, she was discharged with normal physical and radiographic examinations. Dentists and oral surgeons should realize that using air injection equipment can cause life-threatening complications. They should give detailed information to patients about these possible complications and closely follow-up the patients.