Baking soda does help and it's safe as well.

Yes I have heard good things about baking soda and there are certain toothpastes like Arm and Hammer that have it in the toothpaste. I did try that for a while but I can't say that I really noticed much improvement but then I did not keep it up for very long as I did not like the taste much. I do not know how baking soda on its own would work but I suppose that it is worth a try and probably less harmful than some of the bleaches on offer.

I also have the same problem. Though I keep every care to ensure that I keep my teeth clean even then the situation is not improving. I also got it worked upon by a dental student but later again it retained the original condition.

Hi there sand sorry to hear that you have had so much trouble with your teeth and that even after the dental student had worked on them the condition returned. It may be that you have something called porous teeth which I think means that the outer enamel dissolves (which never grows back.) As the enamel gets thinner and more glassy, the yellow dentine centre of the tooth shines through, making the tooth appear yellower. This cause of discolouration is very common in younger people and is usually caused by fizzy drinks etc. I imagine having veneers on your teeth might overcome this but you do need to have a proper diagnosis first.