Numbness of teeth may be caused by metal restorations with current phenomenon, dentin sensitivity, etc., as follows. 1. Metal restorations have current phenomenon: metal restorations have heterogeneous metal restorations, contact with the current phenomenon, resulting in micro-current stimulation of the dental pulp, the symptoms of numbness of the teeth. 2. Dentin sensitivity: acid etching, abrasion, wedge-shaped defects, trauma, etc. can cause exposure of dentin, causing dentin sensitivity, teeth by hot, cold, acidic and sweet and mechanical stimulation, the teeth can have numbness, or even pain. Teeth numbness may have other reasons, it is recommended to go to the hospital in a timely manner, clear cause for targeted treatment.