Dental bleaching, also known as tooth whitening, is a common procedure in general dentistry but most especially in the field of cosmetic dentistry. 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.[citation needed] Teeth can also become stained by bacterial pigments, foodstuffs and tobacco. Certain antibiotic medications (like tetracycline) can also cause teeth stains or a reduction in the brilliance of the enamel.[1]
There are many methods to whiten teeth: bleaching strips, bleaching pen, bleaching gel, laser bleaching, and natural bleaching. Traditionally, at-home whitening involves applying bleaching gel to the teeth using thin guard trays. At-home whitening can also be done by applying small strips that go over the front teeth. Oxidizing agents such as hydrogen peroxide or carbamide peroxide are used to lighten the shade of the tooth. Theoxidizing agent penetrates the porosities in the rod-like crystal structure of enamel and oxidizes interprismatic stain deposits; over a period of time, the dentin layer, lying underneath the enamel, is also bleached. Power bleaching uses light energy to accelerate the process of bleaching in a dental office. The effects of bleaching can last for several months, but may vary depending on the lifestyle of the patient. Factors that decrease whitening include smoking and the ingestion of dark colored liquids like coffee, tea and red wine.
Internal staining of dentine can discolor the teeth from inside out. Internal bleaching can remedy this. If heavy staining or tetracycline damage is present on a patient's teeth, and whitening is ineffective, there are other methods of whitening teeth. Bonding, when a thin coating of composite material is applied to the front of a person's teeth and then cured with a blue light can be performed to mask the staining. A veneer can also mask tooth discoloration.
Dental bleaching, also known as tooth whitening, is a common procedure in general dentistry but most especially in the field of cosmetic
Methods
According to the American Dental Association there are different options to whiten one's teeth that include: in-office bleaching, which is applied by a professional dentist; at-home bleaching, which is to be 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, or other similar places). Whitening products intended for home use include gels, chewing gums, rinses, toothpastes, among others.[2] The ADA has published a list of accepted over-the-counter whitening products to help people choose appropriate whitening products.[3]
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 (includingallergies 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.
There are two main methods of gel bleaching—one performed with high-concentration gel, and another with low-concentration agents. High-concentration bleaching can be accomplished either in the dental office, or at home. Performing the procedure at home is accomplished using high-concentration carbamide peroxide, which is readily available online or in dental stores and is much more cost-effective than the in-office procedure. Whitening is performed by applying a high concentration of oxidizing agent to the teeth with thin plastic trays for a short period of time, which produces quick results. The application trays ideally should be well-fitted to retain the bleaching gel, ensuring even and full tooth exposure to the gel. Trays will typically stay on the teeth for about 15–20 minutes. Trays are then removed and the procedure is repeated up to two more times. Most in-office bleaching procedures use a light-cured protective layer that is carefully painted on the gums and papilla (the tips of the gums between the teeth) to reduce the risk of chemical burns to the soft tissues. The bleaching agent is either carbamide peroxide, which breaks down in the mouth to form hydrogen peroxide, or hydrogen peroxide itself. The bleaching gel typically contains between 10% and 44% carbamide peroxide, which is roughly equivalent to a 3% to 16% hydrogen peroxide concentration.
Low-concentration whitening is far less effective, and is generally only performed at home. Low-concentration whitening involves purchasing a thin mouthguard or strip that holds a relatively low concentration of oxidizing agent next to the teeth for as long as several hours a day for a period of 5 to 14 days. Results can vary, depending on which application is chosen, with some people achieving whiter teeth in a few days, and others seeing very little results or no results at all. Dentists as well as some dental laboratories can fabricate custom fitted whitening trays that will greatly improve the results achieved with an over-the-counter whitening method.
A typical course of bleaching can produce dramatic improvements in the cosmetic appearance of most stained teeth; however, some stains do not respond to bleaching. Tetracycline staining may require prolonged bleaching, as it takes longer for the bleach to reach the dentine layer. Case studies have been performed on people with tetracycline stained teeth. They used custom bleaching trays every night for 6 months and saw dramatic results and improvement. White-spot decalcifications may also be highlighted and become more noticeable directly following a whiting process, but usually calm back down with the other parts of the teeth becoming more white. The white spots become less noticeable, with the other parts of the teeth becoming more white. Bleaching is not recommended if teeth have decay or infected gums. It is also least effective when the original tooth color is grayish and may require custom bleaching trays. Bleaching is most effective with yellow discolored teeth. However, whitener does not work where bonding has been used and neither is it effective on tooth-color filling. Other options to deal with such cases are the porcelain veneers or dental bonding.[4]
Although there is a wide range of whitening products and techniques available, the results after using them may vary from very positive results to almost non-existent results.
The whitening shade guides are used to measure tooth color with Vitapan Classic Shade Guide being the most widely used with 16 shades. These shades determine the effectiveness of the whitening procedure, which may vary from two to seven shades.[5]
Power or light-accelerated bleaching, sometimes colloquially referred to as laser bleaching, uses light energy to accelerate the process of bleaching in a dental office. Different types of energy can be used in this procedure, with the most common being halogen, LED, or plasma arc. Clinical trials have demonstrated that among these three options, halogen light is the best source for producing optimal treatment results.[6] The ideal source of energy should be high energy to excite the peroxide molecules without overheating the pulp of the tooth.[7] Lights are typically within the blue light spectrum as this has been found to contain the most effective wavelengths for initiating the hydrogen peroxide reaction. A power bleaching treatment typically involves isolation of soft tissue with a resin-based, light-curable barrier, application of a professional dental-grade hydrogen peroxide whitening gel (25-38% hydrogen peroxide), and exposure to the light source for 6–15 minutes. Recent technical advances have minimized heat and ultraviolet emissions, allowing a less time-intensive patient preparation procedure. Most power teeth whitening treatments can be done in approximately 30 minutes to one hour, in a single visit to a dental physician. Treatment times and recommendations are dependent on the condition of a person’s teeth at time of treatment. It should be noted that the use in cosmetic dentistry, of concentrations above 0.1% of Hydrogen Peroxide are illegal in the UK, but almost all teeth whitening methods use many times this concentration. Dentists as well as whitening clinics in the UK ignore this law and so far this law has not been enforced.
[edit]Risks
Side effects of teeth bleaching include, but is not limited to:
- Chemical burns from gel bleaching (if a high-concentration oxidizing agent contacts unprotected tissues, which may bleach or discolor mucous membranes), sensitive teeth
- Overbleaching (known in the profession as "over-white teeth") aka "Hyperodonto-oxidation"
- Rebound, or teeth losing the bleached effect, particularly with the intensive treatments (products that provide a large change in tooth colour over a very short treatment period, e.g., 1 hour)
- Pain if you have "sensitive teeth" caused by open dentinal tubules.
- Risk of increased hot/cold sensitivity.
- Increased risk of tongue cancer.[citation needed]
A recent study by Kugel et al. showed that nearly half the initial change in color provided by an intensive in-office treatment (i.e., 1 hour treatment in a dentist's chair) may be lost in seven days.[8]Rebound is experienced when a large proportion of the tooth whitening has come from tooth dehydration (also a significant factor in causing sensitivity).[9] As the tooth rehydrates, tooth color 'rebounds' back toward where it started.[10]
Home tooth bleaching treatments can very slightly reduce tooth enamel.[11] There have been long term Tetracycline studies done where patients received high concentration bleach, over night, for 6 months. These studies show that even over long term exposure, the amount of reduction in tooth enamel is insignificant.[citation needed]
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.[12] 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 prior to 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.
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 also not recommended in pregnant or lactating women.
Tooth whitening does not usually change the color 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 can restore color of fillings, porcelain, and other ceramics when they become stained by foods, drinks, and smoking, among other activities.[citation needed]
Although some over-the-counter bleaching products contain carbamide peroxide, most of them are H2O2 based, which has the potential to interact with DNA. Although there is concern with H2O2carcinogenicity, there is insufficient research to support a conclusion. What the studies have been able to show is that H2O2 is both an irritant and cytotoxic. Clinical studies have found a higher occurrence of gingival irritation when patients use bleaching materials with higher peroxide concentrations.[2]
[edit]Internal bleaching
Internal bleaching procedures are performed on devitalized teeth that have undergone endodontic therapy (a.k.a. "Root Canal") but are discolored due to internal staining of the tooth structure by blood and other fluids that leached in. Unlike external bleaching, which brightens teeth from the outside in, internal bleaching brightens teeth from the inside out. Bleaching the tooth internally involves drilling a hole to the pulp chamber, cleaning, sealing, and filling the root canal with a rubber-like substance, and placing a peroxide gel into the pulp chamber so the gel can work directly inside the tooth on the dentin layer.[citation needed] In this variation of whitening the peroxide is sealed within the tooth over a period of some days and replaced as needed, the so called "walking bleach" technique.[citation needed]
[edit]Agents
Various chemical and physical agents can be used to whiten teeth. Toothpaste typically has small particles of silica, aluminum oxide, calcium carbonate, or calcium phosphate to grind off stains formed by colored molecules that have adsorbed onto the teeth from food. Unlike bleaches, whitening toothpaste does not alter the intrinsic color of teeth.
Bleaching solutions contain peroxide, which bleaches the tooth enamel to change its color.[13] 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.
The FDA of America only approve gels that are under 6% Hydrogen peroxide or 16% or under of Carbamide Peroxide. The Scientific Committee for Consumer Protection of the EU also consider gels containing higher concentrations than mentioned above to be unsafe. Some of the kits on the market are therefore not considered safe if not properly used. For that reason, it is extremely important to closely follow the instructions to avoid any potential dangers.
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