The following are several common causes of oral and maxillofacial infections: 1, odontogenic infection: bacteria enter the body through the focal tooth or periodontal tissue to cause infection, the tooth is anatomically connected to the jawbone, the dental pulp and periodontal infection, which can spread to the root tip, alveolar bone and maxillofacial foveal tissue gap, because caries, periodontal disease, pericoronitis of wisdom teeth are all common clinical diseases, so odontogenic is the most common clinical 2.Glandular origin infection: bacteria invade regional lymph nodes through lymphatic vessels to cause lymphadenitis, and then penetrate the lymph node envelope and spread to the surrounding spaces to form cellulitis, mostly seen in infants and young children, often caused by upper respiratory tract infection; 3.Injury infection: due to trauma mucosal rupture or tooth extraction caused by the destruction of skin mucosal barrier integrity, bacteria enter the body and cause infection; 4.Hematogenous infection 4.Hematogenous infection: purulent infection caused by bacterial bolus of other parts of the body through blood circulation and spread to the oral and maxillofacial area, mostly secondary to systemic sepsis or septicemia, and the condition is often more serious; 5.Medical infection: infection caused by bacteria brought into the body due to poor disinfection during traumatic operations such as local anesthesia in the oral cavity and local puncture in surgery.