A rectangle of flesh behind the incisor may be gingivitis, apical periodontitis, gingival hyperplasia, gum tumor and other diseases. 1. Gingivitis: due to localized plaque and other inflammatory stimuli, it may lead to gum infection, which may be manifested as a rectangle of flesh behind the incisors. 2. Periapical periodontitis: purulent infection around the root tip may lead to pus on the gums, which is manifested as a rectangle of flesh behind the incisors. 3. Gingival hyperplasia: Gingival hyperplasia caused by various reasons of stimulation can also cause a rectangle of flesh behind the incisors. 4. Gum tumors: benign tumors of the gums, such as gum cancer, may also cause a rectangle of flesh behind the incisors. There may be other reasons for the rectangle of flesh behind the incisors, so you need to go to the hospital in time to check the cause of the problem.