Most of the bad breath is caused by local factors. Generally, if you do dental cleaning and filling to solve the local factors first, you will get better. If there is still bad odor, you should see a Chinese medicine practitioner and take some medicine to clear heat and lower fire. If the odor is still there after doing the above treatment, consider removing the crown sleeve if necessary. Xu Dongwei, Department of Oral Medicine, Xiamen Stomatological Hospital.