We usually see white teeth as been healthy, but is this actually true? However toothpastes have whitening agents that proves to give us a shiny white teeth but apparently this do not always do the trick.  

Yellow teeth on the other hand is usually attributed to a poor oral hygiene but fortunately that's not the truth. Research have shown that Yellow teeth are actually stronger than bright white teeth.

There are mainly two things that gives the teeth it color these are the enamel and the dentine. The enamel is that hardest outer translucent part of your teeth that is whitish in color while the dentine which is found beneath the enamel, is naturally yellowish in color. Since the enamel is translucent, the yellowish nature of the dentine shows through the white enamel. This creates a light grey or light yellow color, anything apart from these two colors signifies a poor oral health. 

Research have shown that we should not crave for shinny white teeth because they do not signifies healthiness. Most people tends to use bleaching agents such as "hydrogen peroxide" to whitening their teeth but in reality, this bleach is actually affecting the teeth because it damages the enamel and dentine, and can also cause irritation of the gums.