Hi, I'm only 15 1/2 years old but for a few years now I have had bad breath and yellow teeth. I brush my teeth every day twice a day and I do not consume much coffee and tea. I drink milk and do not take antibiotics. I use mouthwashes and mints all the time but nothing changes. A month ago I used Crest White Strips that cured my yellow teeth and bad breath. However a week later they started developing a yellow color and they are now yellow again and I have bad breath again. Crest White Strips effects are meant to last for 12 months. So I'm not sure what is wrong with me. I don't know if this may be medical or a oral disease. I've tried many remedies, I really don't know what to do now.