The methods to prevent old age caries are as follows: 1. To learn the correct method of brushing teeth. The elderly should choose the health care toothbrush that meets their own hygiene requirements, and it is also recommended to choose the toothpaste containing fluorine, which can prevent root surface caries. In addition to brushing teeth every morning and evening, elderly people should insist on brushing teeth after meal every day, simple rinsing after meal can’t replace brushing teeth. When brushing teeth, it is better to use vertical brushing method with moderate power, each time brush teeth for about three minutes, the power should not be too big to prevent tooth damage; 2. In addition to insist on brushing teeth, it is also very important to clean the gap between teeth. Older people have wider gaps and loose teeth, so brushing alone is not enough to keep them clean. In the condition, it is recommended to use gap brush and dental floss, which can help to clean the soft scale and plaque on the adjacent surface of teeth and effectively prevent the occurrence of root surface caries; 3, remind the elderly friends to pay attention to protect the abutment teeth, when wearing dentures, the dentures are set on top of the abutment teeth, and the abutment teeth should support the dentures. At this time, the abutment teeth are very important, and the abutment teeth should not be neglected when cleaning, and the dentures should be taken out after meals every day, and the dentures and abutment teeth should be cleaned carefully and delicately. If you find any problems with the abutment teeth, such as color change, or sour feeling, go to the specialist hospital in time; 4. Develop the habit of regular oral examination.