Tooth color is highly dynamic. Tooth color changes drastically in the same individual: Our baby teeth are very white, our adult teeth emerge with more yellow hues which tend to become darker as we age. Tooth color also tends to be different within the same person’s mouth; the central incisors “Front teeth” tend to be whiter and brighter than our canines (“eye teeth”) and molars. Even the same tooth has significant color change as we trace from top to bottom. Teeth are thought to get darker as we age for three reasons: 1) Thicker layers yellow dentin develop below our white translucent enamel 2) Enamel gradually wears / thins over the decades 3) Enamel can gather slight staining on the outer surface. Understanding tooth color is an important aspect in fixing a tooth to make is look natural.
Keeping teeth clean in the first place is the best defense for slowing the darkening; whitening and veneers can be used to brighten teeth beyond what cleaning can take care of.