Teeth whitening being one of the most desired procedure in the practice of dentistry is also one of the most available and easiest to achieve. Some dental clinics offer up to nine shades lighter in color. However, this in itself is not necessary as two shades lighter than the original one would usually do.Fortunately, there is no singular standard when it comes to teeth whitening. The most common however is the Vita shade guide. This is subdivided into for shade varieties: We have the brown, the reddish brown, the grey and the reddish grey. The level of darkness also ranges into four categories which is referred to as A, B, C and D.