There are many reasons for a lump in the gums of the lower incisor, such as apical periodontitis, gingival hyperplasia, and gum tumor. 1. Periapical periodontitis: purulent infection of the alveolar bone and periapical tissues of the tooth roots may cause pus in the gums, which will lead to a lump in the gums of the lower incisors. 2. Gingival hyperplasia: localized chronic inflammation, plaque or other stimuli caused by gingival hyperplasia, can also lead to the lower incisor gums up a lump. 3. Gum tumors: Gum tumors, such as benign tumors or malignant tumors, can also lead to a lump in the gums of the lower incisors. There may be other reasons why you need to go to the hospital for examination.