Why do our teeth stain? crest supreme whitening strips reviewSmoking causes yellow and stained teeth First of all, if your teeth aren't perfectly white it's normal! Some people may have naturally pearly whites, but it’s perfectly healthy for the rest of us to have teeth tinged with yellow or grey. Tooth enamel is a thin blueish-white layer and it's translucent, so some of the colour from the dentin beneath shows through. Since dentin is dark yellow, it can give teeth an off-white or yellow appearance. So, your teeth may naturally be more yellow than white. However, your tooth colour could also be caused by staining. Staining can generally be divided into three main categories: Extrinsic: staining caused by food, drink or tobacco that only affects the tooth's enamel Intrinsic: discolouration inside of the tooth, not just on the surface Age-related: enamel gradually wears away with age, exposing more of the yellow dentin underneath So, now that we have discussed what causes the stains on our teeth, let's get stuck into how to whiten them!