The lower incisor is cracked by biting and feels a little loose. Depending on the situation, bonding treatment, composite resin filling, root canal treatment, and fixation can be done. 1. Lower incisor with a very small gap that feels a little loose may be a crown fracture, and the fractured crown part is a little loose. If the looseness of the broken end is obvious and the pulp has not been affected yet, the broken end should be removed and then bonding treatment or composite resin filling should be used. If the pulp has been involved, root canal treatment should also be performed. 2. If the tooth feels a little loose, not the fractured crown part, but the whole tooth, then the use of the tooth should be reduced and fixed. Lower incisor biting something cracked a very small gap feel a little loose recommend timely visit to the hospital, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.