It is best to extract the roots of bad teeth in the elderly, but if the body cannot tolerate extraction and the roots do not show pain, etc., the tooth can be left in place for the time being. Long-term presence of bad root may cause infection, mouth ulcers, affect the service life of dentures, and so on. 1. Infection: bad tooth root may cause infection, which is manifested by repeated swelling and pain in the gums, and may cause jawbone cysts in the long run. 2. Easily cause mouth ulcers: bad tooth roots often have sharp tips, which can easily lead to traumatic mouth ulcers and so on due to the movement of the tongue and mucous membranes. 3. Impact on the service life of dentures: bad tooth roots exist and directly for denture repair, easy to gum swelling and pain, dentures can not be used normally. Elderly with bad tooth roots to the hospital in time, under the advice of the doctor to choose the most reasonable treatment.