The most common reason of bad breath is lack of oral hygiene maintainance. Other common reasons can be gastric regurgitation, diabetes, mouth breathing, dry mouth, lack of adequate water consumption. For oral hygiene... Brush twice daily Clean the tongue and oral soft tissues thoroughly but gently. Use mouthwash. Get ultrasonic scaling done from dentist every 6 months (extremely essential for every individual) Get treatment done for tooth decay from a dentist.

Hi, Bad odour from mouth has multiple causes including deposits on teeth, decayed teeth, food deposits in between teeth or any other extra oral causes such as gastritis. Since you say there are yellow spots on your lower teeth, it may be due to tartar on your teeth. Visit a nearby dentist once and get scaling done. The dentist will also check if bad odour is from any other different source. You can then use chlorhexidine mouthwash for 2 weeks and that should solve the problem, if your bad breath was due to deposit.

Bad breath and Halitosis could be due to multiple reasons. Brush and floss twice a day regularly. Get a clean up done every 6 months along with a general checkup. Get any decay restored. Also, sometimes rootcanal abscesses and periodontal abscesses may also cause bad breath.