There’s a lot of work that goes behind that seemingly easy, pleasant and warm smile, teeth whitening being the commonest cosmetic trick. That’s why over the years, there has been a spurt of DIY (Do-it-Yourself) teeth-whitening kits with very convincing ad campaigns and promises. But are these indeed good for your teeth? Dr Vivek Hegde, past president of the Indian Endodontic Society, says that these come with risks of a worn-out enamel or…