It’s no secret that behind a gorgeous smile are white, bright teeth, which can be tough to maintain, especially as you get older.

When your teeth first come in, they’re protected by a healthy amount of enamel, which is what resists stains and keeps your teeth pearly white. Over time, however, your enamel begins to slowly wear down, allowing more of the brown dentin inside your teeth to show through, which is what creates the yellowing effect.

On top of the natural erosion of your enamel, stains can begin to pile up on your teeth, which starts to resist even professional teeth cleaning. Years of coffee, tea, or smoking can wreak havoc on white teeth, leaving them stained and discolored.

The result is that it becomes more and more difficult to maintain white teeth, which is where periodic teeth whitening can help.