Why discolor your teeth

Stained Teeth is a very common dental problem that makes a lot of people to feel uncomfortable when they have to talk or smile. Discolored teeth require teeth whitening treatment. The acquisition of colored substances onto the tooth pellicle is the main reason that makes teeth to lose their natural white color. Human teeth naturally vary in color. Not all are lucky to have a bright white as the natural color of their teeth. Slightly yellow teeth is normal for most people.
Enamel is usual less translucent, so it is the underlying dentin’s color that determines the tooth color.

Stained teeth, that have lost their natural white color and need teeth whitening, may be the result of many different reasons :
• Colored organic compounds from some foods and drinks – tea, coffee, red wine, curry and other – are absorbed on teeth enamel, resulting in yellow teeth. Other foods that contain much chlorophyll may result in green stains.
• Common dental restorative materials, as the amalgam in silver-colored fillings, may turn adjacent areas of teeth black or gray.
• Antiseptic mouthwashes containing chlorhexidine causing yellow-brown stains on teeth.
• Metallic stains can be caused by metallic salts, such as in iron supplements.
• Systemic disorders (as alkaptonuria, erythropoietic porphyria, hyperbilirubinemia etc.) also can cause tooth discoloration or enamel hypoplasia.
• In fluorosis, chalky white spots or brown marks are caused by excessive fluoride intake. .
• Trauma may cause tooth discoloration . Trauma may change a tooth to a pink, yellow, or dark gray color. Injuries that damage the pulp of a tooth can also cause discoloration.
• Some medications, such as the antibiotics tetracycline and minocycline, may become incorporated into the structure of a tooth, causing intrinsic staining of the teeth with a brown-gray color. Use of tetracyclines should be avoided during the period of tooth formation, from 4th month of pregnancy until 7 years of age.
• Other habits as smoking are also responsible for stained teeth.
• Teeth also change with age. Aging also contributes to the yellowing of teeth. The enamel wears thin, allowing the underlying layer of yellowish dentin to show through.
Tooth discoloration may be classified as either extrinsic (external) or intrinsic (internal)
• Extrinsic discoloration — This occurs when the outer layer of the tooth (the enamel) is stained as by some drinks or foods or by smoking.
• Intrinsic discoloration — This occurs when the inner structure of the tooth (the dentin) darkens or gets a yellow color. Fluorosis or tetracycline stains are examples of common intrinsic stains.
Age-related discoloration — This is a combination of extrinsic and intrinsic factors
http://nhakhoahoangbao.com/en-us/why-discolor-your-teeth.aspx