Tooth whitening is a procedure to lighten teeth and remove stains and discolorations. The peroxide in the bleaching agent penetrates the enamel and breaks down the complex stains(which are darker in nature) into smaller products thereby making the tooth appear lighter in shade.
There are many reasons why teeth become discolored
Some causes of yellowing teeth are beyond our control like discoloration that occurs during ageing. As we age, the tooth enamel thins, thus making our teeth to appear more yellow in colour.
Extrinsic stains i.e., superficial stains that occur on the outer surface of the tooth are easier to treat compared to intrinsic stains whether they are congenital or acquired. In most cases, professional teeth whitening treatments can restore your smile’s former glory and give you back the ability to smile without feeling embarrassed. Severe discolorations may be best treated with microabrasion and subsequent bleaching to achieve desirable results. Dental whitening may be accomplished by using either professional or at-home bleaching modalities.
Before a decision is made that tooth bleaching is the best possible treatment available for the patient, the dentist takes a thorough patient history that would include the patient’s opinions regarding the cause of tooth discoloration, any history of allergies, especially to the ingredients used in bleaching materials, information regarding any past problems with tooth sensitivity which has to be investigated carefully to determine the cause(s) and whether treatment before tooth bleaching will benefit the patient.
Additional examination considerations include tooth/enamel cracks, exposed root surfaces and other smile considerations such as translucency or defects in tooth form or anatomy.
Some tooth discolorations may be the result of a disease or condition that requires root canal therapy, restorations or dental surgery.
Examination of tooth function and para-function may reveal conditions such as bruxism (involuntary grinding of teeth) or temporomandibular joint dysfunction. If not examined properly, these conditions may be aggravated by the use of bleaching trays that are prescribed by dentists.
Patient habits (tobacco, alcohol, food habits) and lifestyle, as well as the presence of removable or fixed appliances, should also be considered during an examination.
In pregnant or lactating women, teeth whitening is not recommended as in these cases, due to hormonal changes gums become inflamed and sensitive and the bleaching agents used can aggravate the condition.
Tooth-colored fillings and resin composite materials used in dental restorations like the crowns, veneers and bridges do not whiten. Therefore, using a whitening agent on teeth that do and do not contain restorations will result in uneven whitening. The teeth without restorations appear lighter than those with restorations. Therefore, any whitening procedure should be done prior to the placement of composite fillings, veneers, crowns, dentures, or porcelain restorations in order to best match the degree of whitening to your new tooth color.
For the enamel to remineralize and optimize the bonding strength, a minimum of 2 weeks following a whitening procedure should be allowed before any prosthesis is given. Tooth colored fillings will have to be replaced after the bleaching process is completed so as to avoid shade mismatch.
Bleaching is not recommended in children under the age of 16 because the pulp chamber, or nerve of the tooth, is bigger and wider until this age. Teeth whitening under this condition could irritate the pulp or cause it to become sensitive. Also, the enamel of a primary tooth is thinner when compared to the permanent tooth, because of this tooth coloration within a dental arch may vary significantly during the mixed dentition stage of the patient. If a full arch cosmetic bleaching is done during this developmental stage, it would result in mismatched dental appearance once the child is in the permanent dentition stage. Adolescents have unique dental needs to maintain their self-image. Tooth whitening has been a
successful procedure for adolescent patients.
Patients with these conditions should always consult with their dentist prior to using a tooth whitening system. Individuals with gum disease or teeth with worn enamel are generally discouraged from undergoing a tooth whitening procedure because bleaching aggravates sensitivity in such patients.
Tooth decay has to be treated before undergoing any whitening procedure because the whitening solutions can penetrate into the decay and the inner areas of the tooth, which can cause sensitivity. Also, whitening procedures will not work on exposed tooth roots because roots do not have an enamel layer to absorb the bleaching agent. Roots resist the bleaching agents.
People who are allergic to teeth whitening agents like peroxide are contraindicated for bleaching procedure.
Such patients are also contraindicated in whom sensitivity occurs due to cracked or chipped teeth.
Sometimes tooth becomes sensitive when vital bleaching is done. This is due to permeation of enamel and dentin by hydrogen peroxide resulting in a mild, transient inflammatory response. It should not be used at high concentrations and for extended period of time. This kind of tooth sensitivity can be managed with the use of non-steroidal anti-inflammatory drugs (NSAIDs), fluoride, casein phosphopeptide-amorphous calcium phosphate or potassium nitrate containing products.
Individuals who expect their teeth to become brilliant white may be disappointed with the results of bleaching. Bleaching definitely makes the teeth 2 shades lighter but not completely white. In the case of smokers, limited results will be seen unless the habit of smoking is ceased, particularly during the bleaching process.
Taking all the above-mentioned details into consideration, it can be concluded that, the best candidates for professional teeth whitening are those who have healthy teeth without fillings or restorations and healthy gum tissues. Better results with bleaching can be seen in patients whose teeth have a yellowish shade.