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Dental bleaching, also known as tooth whitening, is a common procedure in general dentistry. According to the FDA, whitening restores natural tooth colour and bleaching whitens beyond the natural colour. There are many methods available, such as brushing, bleaching strips, bleaching pen, bleaching gel, and laser bleaching. Teeth whitening has become the most requested procedure in cosmetic dentistry today. More than 100 million Americans whiten their teeth one way or another; spending an estimated $15 billion in 2010.
Bleaching methods use carbamide peroxide which reacts with water to form hydrogen peroxide. Carbamide peroxide has about a third of the strength of hydrogen peroxide. This means that a 15% solution of carbamide peroxide is the rough equivalent of a 5% solution of hydrogen peroxide. The peroxide oxidizing agent penetrates the porosities in the rod-like crystal structure of enamel and breaks down stain deposits in the dentin. Power bleaching uses light to accelerate the process of bleaching in a dental office. Another bleaching agent is 6-phthalimido peroxy hexanoic acid (PAP).
Tooth bleaching is not a modern invention. Ancient Romans, for example, used urine and goat milk in an attempt to make and keep their teeth whiter.
CAUSES OF TOOTH DISCOLORATION
A child's deciduous teeth are generally whiter than the adult teeth that follow. As a person ages the adult teeth often become darker due to changes in the mineral structure of the tooth, as the enamel becomes less porous and phosphate-deficient. Teeth can become stained by bacterial pigments, food-goods and vegetables rich with carotenoids or xanthonoids. Certain antibacterial medications (like tetracycline) can cause teeth stains or a reduction in the brilliance of the enamel. Ingesting coloured liquids like coffee, tea, and red wine can discolour teeth.
According to the American Dental Association, different whitening methods include in-office bleaching, which is applied by a professional dentist; at-home bleaching, which is used at home by the patient; over-the-counter, which is applied by patients; and options called non-dental, which are offered at mall kiosks, spas, salons etc.
The ADA recommends to have one's teeth checked by a dentist before undergoing any whitening method. The dentist should examine the patient thoroughly: take a health and dental history (including allergies and sensitivities), observe hard and soft tissues, placement and conditions of restorations, and sometimes x-rays to determine the nature and depth of possible irregularities.
The whitening shade guides are used to measure tooth colour. These shades determine the effectiveness of the whitening procedure, which may vary from two to seven shades. The effects of bleaching can last for several months, but may vary depending on the lifestyle of the patient. Dentures can be whitened using denture cleaners.
White-spot decalcification may be highlighted and become more noticeable directly following a whiting process, but with further applications the other parts of the teeth usually become more white and the spots less noticeable. Bleaching is not recommended if teeth have decay or infected gums. It is least effective when the original tooth colour is greyish and may require custom bleaching trays. Bleaching is most effective with yellow discoloured teeth. However, whitener does not work where bonding has been used and neither is it effective on tooth-colour filling. Other options to deal with such cases are the porcelain veneers or dental bonding.
Internal staining of dentin can discolour the teeth from inside out. Internal bleaching can remedy this on root canal treated teeth. If heavy staining or tetracycline damage is present on a patient's teeth, and whitening is ineffective (tetracycline staining may require prolonged bleaching, as it takes longer for the bleach to reach the dentin layer), there are other methods of masking the stain. Bonding, which also masks tooth stains, is when a thin coating of composite material is applied to the front of a person's teeth and then cured with a blue light. A veneer can also mask tooth discoloration.
An alternative to the walking bleach procedure is the inside-out bleach where the bleaching cavity is left open and the patient issued with a custom-formed tray to place and retain the agent, typically a carbamide peroxide gel inside the cavity. On review once sufficient shade change has occurred the access cavity can be sealed, typically with a dental composite.
Apples, celery and carrots support and help whitening teeth, as they act like natural stain removers by increasing saliva production (the mouth's self-cleaning agent) and scrub the teeth clean. They help maintain a fresh breath by killing bacteria that produces halitosis. The juice of apples, especially green apples, contains malic acid.
Side effects of teeth bleaching include, but are not limited to:
A recent study by Kugel et al. showed that nearly half the initial change in colour provided by an intensive in-office treatment (i.e., 1 hour treatment in a dentist's chair) may be lost in seven days. Rebound is experienced when a large proportion of the tooth whitening has come from tooth dehydration (also a significant factor in causing sensitivity). As the tooth rehydrates, tooth color 'rebounds' back toward where it started.
Home tooth bleaching treatments can have significant negative effects on tooth enamel.
The side effects that occur most often are a temporary increase in tooth sensitivity and mild irritation of the soft tissues of the mouth, particularly the gums. Tooth sensitivity often occurs during early stages of the bleaching treatment. Tissue irritation most commonly results from an ill-fitting mouthpiece tray rather than the tooth-bleaching agent. Both of these conditions usually are temporary and disappear within 1 to 3 days of stopping or completing treatment. Individuals with sensitive teeth and gums, receding gums and/or defective restorations should consult with their dentist before using a tooth whitening system. People who are sensitive to hydrogen peroxide (the whitening agent) should not try a bleaching product without first consulting a dentist. Also, prolonged exposure to bleaching agents may damage tooth enamel. This is especially the case with home remedy whitening products that contain fruit acids and brushing with abrasives such as baking soda.
Tooth whitening does not usually change the colour of fillings and other restorative materials. It does not affect porcelain, other ceramics, or dental gold. However, it can slightly affect restorations made with composite materials, cements and dental amalgams. Tooth whitening will not restore colour of fillings, porcelain, and other ceramics when they become stained by foods, drinks, and smoking, as these products are only effective on natural tooth structure.
Bleaching is not recommended in children under the age of 16. This is because the pulp chamber, or nerve of the tooth, is enlarged until this age. Tooth whitening under this condition could irritate the pulp or cause it to become sensitive. Tooth whitening is not recommended in pregnant or lactating women.
Bleaching solutions contain peroxide, which bleaches the tooth enamel to change its colour. Off-the-shelf products typically rely on a carbamide peroxide solution varying in concentration from 10% to 44%. Bleaching solutions may be applied directly to the teeth, embedded in a plastic strip that is placed on the teeth or use a gel held in place by a mouthguard.
Sodium perborate is also used as a tooth bleaching agent.
Studies have shown that hydrogen peroxide is an irritant and cytotoxic. At concentrations of 10% or higher, hydrogen peroxide is potentially corrosive to mucous membranes or skin and can cause a burning sensation and tissue damage.
The US FDA only approves gels that are under 6% hydrogen peroxide or 16% or less of carbamide peroxide. The Scientific Committee for Consumer Protection of the EU consider gels containing higher concentrations than these to be unsafe.
There are non-peroxide products in the market that can help to whiten teeth.
To read more about tooth whitening, please click on the following link: http://en.wikipedia.org/wiki/Tooth_bleaching