Medical conditions that can cause yellowing include trauma, drugs and simply aging.
For example, the antibiotic tetracycline, if taken during childhood, can cause discolorations in the permanent teeth ranging from gray to brown to yellow.
As we age, some teeth slowly devitalize. This often means the pulp or nerve chamber slowly calcifies and strangles itself from the blood supply. This in turn usually gives the tooth a more yellow hue.
In a similar way, trauma to the tooth may sever crucial blood supply to dental nerves and cause yellow to darker gray discoloration. Probably the most common reason for yellowing teeth is staining from foods and tobacco use. The prevalence of soft drinks -- which are very acidic -- also contribute to the yellowing and staining of teeth. This has led to the teeth bleaching revolution which can reverse the effects of extrinsic yellowing.
Everyone is born with certain genetic traits that affect the shade of their teeth. While bleaching products can brighten teeth to some degree, they may not significantly alter those traits.
Joseph R. Anderson, DDS - General and Cosmetic Dentistry Providing family dental care, cosmetic dentistry and preventive services to residents of Lake Conroe and surrounding areas – including Montgomery, Conroe, Cleveland, Willis, The Woodlands,and Houston,TX.