Possible causes of soft teeth include dentin sensitivity, periodontitis, apical periodontitis and so on. 1. Dentin sensitivity: If there is dentin sensitivity, when eating some stimulating foods such as sweet and sour foods, there will be soreness and tenderness of the teeth. You can use desensitizing toothpastes such as those containing potassium nitrate or strontium chloride, and you should avoid chewing hard foods. 2. Periodontitis: If there is periodontitis, gum recession is likely to occur, followed by loose teeth, there will be teeth soft and weak phenomenon. Periodontal treatment should be carried out in a timely manner. 3. Periapical periodontitis: Periapical periodontitis will appear when the teeth bite pain, tooth loosening and soft feeling, should be carried out in a timely manner for root canal treatment. If there is obvious tooth softness, go to the hospital in time for examination and timely treatment.