TEETH WHITENING
In the exciting world of cosmetic dentistry, teeth whitening is the most popular dental services provided. For Men and women alike, your smile is important. It's one of the first things people notice. Teeth whitening can make those moments even more impressionable. It is the perfect time to feel better about you smile.

Why do my teeth have stains and discolorations? Most stains are caused by age, tobacco, coffee, or tea. Other types of stains can be caused by antibiotics, such as tetracycline; or too much fluoride.

Tooth bleaching, also known as tooth whitening, is a common procedure in general dentistry but most especially in the field of cosmetic dentistry. Many people consider white teeth to be an attractive feature of a smile. 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. Teeth can also become stained by bacterial pigments, foodstuffs and tobacco.

The procedure to bleach teeth uses oxidizing agents such as hydrogen peroxide or carbamide peroxide to lighten the shade of the tooth. The oxidizing 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. The effects of bleaching can last for several months, but may be shortened by cigarette smoking, and tea and coffee consumption.

Methods
There are two main methods of bleaching--one performed by a dentist and one self-performed. A dentist applies a high concentration of oxidizing agent for a short period of time, which produces quick results. In order to reduce the risk of chemical burns to the soft tissues, 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). 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 up to 35% carbamide peroxide which is roughly equivalent to a 12% hydrogen peroxide concentration.

At-home 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. This is known as take-home or over-the-counter bleaching. 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. Whitening is potentially better at a dentist because the strip or mouth-guard does not completely conform to the shape of the teeth, sometimes leaving the tips of the teeth (near the gumline) unbleached. The bleaching agent is typically less than 10% hydrogen peroxide equivalent so irritation to the soft tissue around teeth is minimized. Dentists as well as some dental laboratories can fabricate custom fitted whitening trays that will greatly improve the results you can achieve with an "at home" 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. White-spot decalcifications may also be highlighted and become more noticeable. Bleaching is least effective if teeth have white spots, decay or infected gums. It is also least effective when the original tooth color is grayish. Bleaching is most effective with yellow discolored teeth.

Recently, efforts have been made to accelerate the bleaching process by the use of light. Studies have shown varying results as to the efficacy of light-activated bleaching.

Risks
Side effects of tooth bleaching include: chemical burns (if a high-concentration oxidizing agent contacts unprotected tissues, which may bleach or discolor mucous membranes), sensitive teeth, and overbleaching (known in the profession as "over white teeth"). Rebound, or teeth losing the bleached effect and darkening, is also an issue, with some studies showing the rebound effect over 30 days. A recent study by Kugel et al has shown that as much as 4 shades of lightness can be lost over 30 days with light-activated/office bleaching.

The two 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 prior to using a tooth whitening system. Anyone allergic to peroxide (the whitening agent) should not use a bleaching product. 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 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 can restore colour of fillings, porcelain, and other ceramics when they become stained by foods, drinks, and smoking, amongst other activities.

Bleaching vs. Whitening

According to the FDA, the term "bleaching" is permitted to be used only when the teeth can be whitened beyond their natural color. This applies strictly to products that contain bleach — tycally hydrogen peroxide or carbamide peroxide. The term "whitening," on the other hand, refers to restoring a tooth’s surface color by removing dirt and debris. So any product that cleans (like a toothpaste) is considered a whitener. Of course, the term whitening sounds better than bleaching, so it is more frequently used — even when describing products that contain bleach.

The Two Types of Tooth Stains

There are two categories of staining as it relates to the teeth: extrinsic staining and intrinsic staining.

Extrinsic stains are those that appear on the surface of the teeth as a result of exposure to dark-colored beverages, foods and tobacco, and routine wear and tear. Superficial extrinsic stains are minor and can be removed with brushing and prophylactic dental cleaning. Stubborn extrinsic stains can be removed with more involved efforts, like teeth bleaching. Persistent extrinsic stains can penetrate into the dentin and become ingrained if they are not dealt with early.

Intrinsic stains are those that form on the interior of teeth. Intrinsic stains result from trauma, aging, exposure to minerals (like tetracycline) during tooth formation and/or excessive ingestion of fluoride. In the past, it was thought that intrinsic stains were too resistant to be corrected by bleaching. Today, cosmetic dentistry experts believe that even deep-set intrinsic stains can be removed with supervised take-home teeth whitening that is maintained over a matter of months or even a year.

What Causes Tooth Staining?

Age: There is a direct correlation between tooth color and age. Over the years, teeth darken as a result of wear and tear and stain accumulation. Teenagers will likely experience immediate, dramatic results from whitening. In the twenties, as the teeth begin to show a yellow cast, teeth-whitening may require a little more effort. By the forties, the yellow gives way to brown and more maintenance may be called for. By the fifties, the teeth have absorbed a host of stubborn stains which can prove difficult (but not impossible) to remove.

Starting color: We are all equipped with an inborn tooth color that ranges from yellow-brownish to greenish-grey, and intensifies over time. Yellow-brown is generally more responsive to bleaching than green-grey.

Translucency and thinness: These are also genetic traits that become more pronounced with age. While all teeth show some translucency, those that are opaque and thick have an advantage: they appear lighter in color, show more sparkle and are responsive to bleaching. Teeth that are thinner and more transparent — most notably the front teeth — have less of the pigment that is necessary for bleaching. According to cosmetic dentists, transparency is the only condition that cannot be corrected by any form of teeth whitening.

Eating habits: The habitual consumption of red wine, coffee, tea, cola, carrots, oranges and other deeply-colored beverages and foods causes considerable staining over the years. In addition, acidic foods such as citrus fruits and vinegar contribute to enamel erosion. As a result, the surface becomes more transparent and more of the yellow-colored dentin shows through.

Smoking habits: Nicotine leaves brownish deposits which slowly soak into the tooth structure and cause intrinsic discoloration.

Drugs / chemicals: Tetracycline usage during tooth formation produces dark grey or brown ribbon stains which are very difficult to remove. Excessive consumption of fluoride causes fluorosis and associated areas of white mottling.

Grinding: Most frequently caused by stress, teeth grinding (gnashing, bruxing, etc.) can add to micro-cracking in the teeth and can cause the biting edges to darken.

Trauma: Falls and other injuries can produce sizable cracks in the teeth, which collect large amounts of stains and debris.

Hydrogen Peroxide vs. Carbamide Peroxide

The bleach preference for in-office whitening, where time is limited, is powerful and fast-acting hydrogen peroxide. When used in teeth bleaching, hydrogen peroxide concentrations range from approximately nine percent to 40 percent.

By contrast, the bleach of preference for at-home teeth whitening is slower acting carbamide peroxide, which breaks down into hydrogen peroxide. Carbamide peroxide has about a third of the strength of hydrogen peroxide. This means that a 15 percent solution of carbamide peroxide is the rough equivalent of a five percent solution of hydrogen peroxide.

In-Office Teeth Whitening

Professional in-office teeth whitening is the most popular cosmetic dental procedure in the world today. Unlike home-use whitening systems that incorporate low-dose bleaching agents, in-office whitening (also known as power bleaching, power whitening, professional whitening or chairside whitening) takes place under carefully monitored conditions which allow for the safe, controlled, pain-free use of a relatively high concentration of bleaching gel — yielding results that are visible immediately.

Advantages of In-Office Whitening

* No other teeth whitening procedure produces faster results.
* This is the safest form of tooth bleaching.
* Gum and tooth sensitivity (formerly drawbacks to in-office bleaching) are more controllable today due to thicker peroxide gels (that don’t soak into the teeth as much as previous gels) and the use of desensitizers such as potassium nitrate and fluoride.

Disadvantages of In-Office Whitening

* In-office bleaching is more expensive than take-home alternatives. Its cost, on average, is $650, compared to $400 for take-home trays and under $100 for over-the-counter bleaching trays or whitening strips.
* Results can be unpredictable, depending on factors such as age, heredity and the type of staining that is present.
* In-office bleaching is not a permanent solution. Shortly after treatment is completed, the teeth resume accumulating stains. Many dentists therefore recommend home maintenance follow-up with a lower-percentage bleach that can be kept on the teeth for longer periods of time.

Stains That are Best Removed with In-Office Whitening

Chairside whitening removes organic stains or discolorations primarily caused by:

* Aging. Over time, the teeth darken with a yellow, brown, green or grey cast (which may be due to heredity and/or eating habits). Yellowed teeth tend to whiten most readily.
* Consumption of certain foods (notably coffee, red wine, sodas and dark-colored vegetables and fruits).
* Tobacco use.

Stains Resistant to In-Office Whitening

* Teeth with certain stains — typically those that are inorganic — do not respond well to in-office whitening. In fact,
these teeth may look even darker after the surrounding teeth have been whitened.
* Trauma, which causes the dentin to darken.
* Tetracycline antibiotics ingested during tooth-formation. These drugs chemically bind with the crystalline structure of both the tooth’s enamel and underlying dentin.
* Overexposure to fluoride, which can cause fluorosis, resulting in tooth discoloration.

The In-Office Teeth Whitening Procedure

Typically, the steps involved are not painful or uncomfortable; in fact, many patients doze or watch a DVD or TV during the procedure.

* A cheek retractor is inserted into the mouth, exposing all the “esthetic zone” teeth (teeth that are visible when you smile).

* A liquid rubber dam or hardening resin is painted onto the gum tissue to protect against any irritation caused by the bleaching gel.

* A bleaching gel containing hydrogen peroxide is applied to the esthetic zone teeth and kept on for approximately 15 to 30 minutes.

* The bleaching gel is suctioned or washed off, and fresh gel is applied for one or more additional periods of 15 to 30 minutes. The ultraviolet light is designed to enhance the in-office bleaching process.

* Some whitening treatments incorporate an intense light that is focused on the teeth and is said to activate or enhance the bleaching process. Opinions vary as to whether this light improves the bleaching outcome.

* Between gel applications, the teeth are checked to see how well they have whitened, and whether more bleach needs to be applied.

* After the final gel application, the cheek retractors are removed, the patient rinses and the immediate post-treatment shade change is measured. The teeth may whiten by as few as two to three shades or as many as eight (out of a total of 16). Part of the whitening effect is due to dehydration during the bleaching process, which makes the teeth look whiter than their true new color. That color will emerge after a couple of days.

If a satisfactory level of whitening hasn’t been achieved, your dentist may recommend follow-up in-office bleaching at a future date, and/or a regimen of take-home bleaching trays.