In the various layers of tissue in the maxillofacial area, such as muscle and bone, muscle and muscle are interstitial, when the infection invades the interstitial space so that the soft tissue swells to form purulent inflammation, it is called interstitial infection. Oral interstitial infections are secondary infections, that is, they originate from other places, and the causes of infection are as follows: 1. Infections from the teeth: for example, the most common wisdom teeth pericoronitis, periapical periodontitis, jaw bone osteomyelitis, etc.; 2. Infections from the salivary glands: they can be caused by the spread of tonsillitis, salivary adenitis, maxillofacial lymphadenitis, etc. 3. Others: such as traumatic infections, infections of medical origin, and through the blood transmission from other parts of the body infections, etc., but nowadays it is less common.