Healthy teeth and a bright smile are features widely associated with an attractive appearance. Yellow teeth are generally considered less attractive than whiter teeth, so it is helpful to know the causes of yellow teeth. Teeth may turn yellow for many reasons, including staining, erosion of the outer layer or a systemic process.
Teeth may turn yellow due to staining of the outer layer of white enamel. Smoking is a common cause of staining and can turn the the teeth yellow, brown or black. A British study published in the August 2008 issue of "BMC Public Health" reported that, of the 3,384 adults in the sample study, 28 percent of smokers had severe or moderate teeth discoloration, compared with 15 percent of nonsmoking adults. Chewing tobacco also contributes to yellowing of the teeth.
Food and Drink Stains
Dark-colored foods, drinks and spices can stain the teeth, causing a yellow appearance. Common drinks and foods that stain teeth include coffee, tea, curry, turmeric, dark-colored berries and deep-hued sauces. Some less prevalent foods, such as acai, have been found to cause stains on teeth. There are several ways to prevent excessive yellow staining of the teeth, including drinking dark beverages with a straw, drinking water after consuming dark-pigmented food and beverages, and brushing teeth after a meal.
Thinning Tooth Enamel
When the white outer surface layer of teeth, called the enamel, becomes thinner, it exposes the dentin -- the yellow layer beneath it -- thereby giving teeth a yellow appearance. A number of foods and drinks are inherently acidic. When they are consumed, they produce an abrasive effect on the outer enamel surface of teeth, causing yellowing of the teeth. Some foods and beverages that can cause erosion of tooth enamel and consequent yellow teeth include cola, orange juice, sports drinks, lemonade, cranberries, tomatoes, artificial sweeteners and most alcoholic beverages. Illnesses associated with excessive vomiting contribute to acidity in the mouth and often cause yellow teeth.
Some dental devices and orthodontic treatments treatments may cause yellow teeth. An article published in the July 2013 issue of "American Journal of Orthodontics" detailed a study that followed 34 participants receiving orthodontic treatment. Objective color measurements documented significant yellowing of teeth with the use of orthodontic treatments and the sealants used to bind the orthodontic fixtures. Some sealants used in dental care treatments can cause decalcification, which may contribute to yellowing of teeth. Various dental products are available and they may vary in their effects on tooth color. The selection of hardware and sealants is based on the best function as well as cosmetic results.
Medication and Illness
High levels of fluoride exposure in early childhood can cause tooth discoloration. Medications such as tetracycline and amoxicillin can cause yellow teeth due to systemic effects, particularly in children. Additionally, health conditions that affect normal liver function result in high levels of bilirubin, a breakdown product that may cause yellow discoloration of the skin and teeth.
Tooth color, like many other physical characteristics, is slightly variable among individuals, and some people may be more prone to a yellow hue, while others may inherently have whiter teeth. Aging is associated with increasingly yellow tinge of teeth. Men are more likely to have yellow teeth than women, although the reasons are not clear.