A tooth that has been filled and has a foul odor oozing out, may have secondary decay in the tooth. In this case, the original filling material, and the new decayed part can be removed, and then the tooth can be filled and replenished directly to restore their connection. The odor may also be due to the presence of food embedded in the adjacent surfaces of the teeth, causing redness, swelling, and pain in the gums, and in this case the odor of decay may also appear. It may also be due to a tooth that has lost its filling material and is decaying, or has a nerve leak. In this case, root canal treatment and direct protection of the tooth is required, followed by restoration of the tooth with braces, which can prevent the tooth from fracturing.