Why Do Teeth Become Discoloured Over Time?

Teeth darken for many reasons — some visible, some hidden. Even with diligent brushing, stains can seep deeper into enamel or arise from internal changes. Below are the most common causes:

What Are The Causes For Teeth Become Darker

Habitual Staining
Regular consumption of pigmented drinks and foods can gradually stain enamel. Think tea, coffee, red wine, and deeply coloured vegetables. Over time, repeated exposure leaves a layer of discolouration on the outer surfaces of the teeth.
Tobacco Use
Smoking or using tobacco products deposits tar and nicotine on your teeth. These compounds penetrate enamel and leave a persistent yellow-brown tint, dulling your smile.
Enamel Wear and Ageing
As we age, our tooth enamel slowly wears down. Because enamel is naturally semi-translucent, thinner enamel makes the underlying dentine — which is more yellow—become more visible. This gives teeth an overall darker, more muted tone.
Internal Changes in Tooth Vitality
If a tooth’s nerve or pulp is damaged (due to decay, trauma, or previous treatment), it may lose vitality. Over time, this can lead to a greyish or darker hue developing internally—something that regular cleaning alone cannot reverse.

Even perfect brushing may not be enough to fully reverse these stains, because many of them affect deeper tooth structure. That’s where professional teeth whitening or bespoke treatments can make the difference.