Age: There is a direct correlation between tooth color and age. Over the years, teeth darken as a result of wear and tear and stain accumulation. Teenagers will likely experience immediate, dramatic results from whitening. In the twenties, as the teeth begin to show a yellow cast, whitening may require a little more effort. By the forties, the yellow gives way to brown, and more maintenance may be called for. By the fifties, the teeth had absorbed a host of stubborn stains that could prove difficult (but not impossible) to remove.

Starting color: We are all equipped with an inborn tooth color that ranges from yellow-brownish to greenish-grey, and intensifies over time. Yellow-brown is generally more responsive to bleaching than green-grey.

Translucency and thinness are also genetic traits that become more pronounced with age. While all teeth show some translucency, those that are opaque and thick have an advantage: they appear lighter in color, show more sparkle, and are responsive to bleaching. Teeth that are thinner and more transparent – most notably the front teeth – have less of the pigment that is necessary for bleaching. According to cosmetic dentists, the only issue that no teeth whitening method can fix is transparency.