Tooth bleaching

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.^[1] 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. Teeth whitening under this condition could irritate the pulp or cause it to become sensitive. Teeth 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.^{[citation needed]}

Teeth Whitening: Customize Your Bright, White Smile

In the blossoming world of cosmetic dentistry, teeth whitening reigns supreme. Universally valued by men and women alike, whitening (or bleaching) treatments are available to satisfy every budget, time frame and temperament.

Whether in the form of one-hour bleaching sessions at your dentist’s office, or home-use bleaching kits purchased at your local drugstore, teeth whitening solutions abound. Yet only 15 percent of the population has tried the cosmetic procedure, and misinformation on the subject is rife.

The long and the short of it is that teeth whitening works. Virtually everyone who opts for this cosmetic treatment will see moderate to substantial improvement in the brightness and whiteness of their smile. However, teeth whitening is not a permanent solution and requires maintenance or "touch-ups" for a prolonged effect.

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 — typically 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.

Why Teeth Whitening? Examining Enamel

Most of us start out with sparkling white teeth, thanks to their porcelain-like enamel surface. Composed of microscopic crystalline rods, tooth enamel is designed to protect the teeth from the effects of chewing, gnashing, trauma and acid attacks caused by sugar. But over the years enamel is worn down, becoming more transparent and permitting the yellow color of dentin — the tooth’s core material — to show through.

During routine chewing, dentin remains intact while millions of micro-cracks occur in the enamel. It is these cracks, as well as the spaces between the crystalline enamel rods, that gradually fill up with stains and debris. As a result, the teeth eventually develop a dull, lackluster appearance.

Teeth whitening removes the stains and debris, leaving the enamel cracks open and exposed. Some of the cracks are quickly re-mineralized by saliva, while others are filled up again with organic debris.

Tooth Discoloration: 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.

Teeth Whitening options

Three major teeth whitening options are available today. All three rely on varying concentrations of peroxide and varying application times.

In-Office Whitening

Significant color change in a short period of time is the major benefit of in-office whitening. This protocol involves the carefully controlled use of a relatively high-concentration peroxide gel, applied to the teeth by the dentist or trained technician after the gums have been protected with a paint-on rubber dam. Generally, the peroxide remains on the teeth for several 15 to 20 minute intervals that add up to an hour (at most). Those with particularly stubborn staining may be advised to return for one or more additional bleaching sessions, or may be asked to continue with a home-use whitening system.

Professionally Dispensed Take-Home Whitening Kits

Many dentists are of the opinion that professionally dispensed take-home whitening kits can produce the best results over the long haul. Take-home kits incorporate an easy-to-use lower-concentration peroxide gel that remains on the teeth for an hour or longer (sometimes overnight). The lower the peroxide percentage, the longer it may safely remain on the teeth. The gel is applied to the teeth using custom-made bleaching trays that resemble mouth guards.

Over-the-Counter Whitening

The cheapest and most convenient of the teeth whitening options, over-the-counter bleaching involves the use of a store-bought whitening kit, featuring a bleaching gel with a concentration lower than that of the professionally dispensed take-home whiteners. The gel is applied to the teeth via one-size-fits-all trays, whitening strips or paint-on applicators. In many cases this may only whiten a few of the front teeth unlike custom trays that can whiten the entire smile.

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.

How White Can You Go? A Matter of Esthetics

Teeth whitening results are subjective, varying considerably from person to person. Many are immediately delighted with their outcome, while others may be disappointed. Before you embark on any whitening treatment, ask your dentist for a realistic idea of the results you are likely to achieve and how long it should take to achieve them. Expectations play a major role in teeth whitening.

Whitening Shade Guides

In the dental office, before-and-after tooth color is typically measured with shade guides. These are hand-held displays of wide ranges of tooth colors. (Dentists also use them in choosing crown and other restoration shades.)

The standard-setter among them has long been the Vitapan Classic Shade Guide. This shade guide standard incorporates 16 shades, systematically arranged from light to dark into four color groups, and provides a universal tooth-color terminology.

While whitening can occasionally lighten tooth color by nine or more shades, most of those who bleach their teeth are likely to see a change of two to seven shades.

Teeth Whitening Risks

Teeth whitening treatments are considered to be safe when procedures are followed as directed. However, there are certain risks associated with bleaching that you should be aware of:

• Sensitivity: Bleaching can cause a temporary increase in sensitivity to temperature, pressure and touch. This is likeliest to occur during in-office whitening, where higher-concentration bleach is used. Some individuals experience spontaneous shooting pains (“zingers”) down the middle of their front teeth.

Individuals at greatest risk for whitening sensitivity are those with gum recession, significant cracks in their teeth or leakage resulting from faulty restorations. It has also been reported that redheads, including those with no other risk factors, are at particular risk for tooth sensitivity and zingers.

Whitening sensitivity lasts no longer than a day or two, but in some cases may persist up to a month. Some dentists recommend a toothpaste containing potassium nitrate for sensitive teeth.

• Gum irritation: Over half of those who use peroxide whiteners experience some degree of gum irritation resulting from the bleach concentration or from contact with the whitening trays. Such irritation typically lasts up to several days, dissipating after bleaching has stopped or the peroxide concentration lowered.
• Technicolor teeth: Restorations such as bonding, dental crowns or porcelain veneers are not affected by bleach and therefore maintain their default color while the surrounding teeth are whitened. This results in what is frequently called “technicolor teeth.”

Maintaining Your Whiter Smile

To extend the longevity of newly whitened teeth, dentists are likely to recommend:

• At-home follow-up or maintenance whitening — implemented immediately or performed as infrequently as once a year.
• Avoiding dark-colored foods and beverages for at least a week after whitening.
• Whenever possible, sipping dark-colored beverages with a straw.
• Practicing excellent oral hygiene — brushing and flossing after meals and at bedtime.

Caveats

In addition to the aforementioned risk factors, a number of caveats should be considered before undergoing teeth whitening:

• No amount of bleaching will yield “unnaturally” white teeth.
• Whitening results are not fully seen until approximately two weeks after bleaching. This is an important consideration if you are about to have ceramic restorations and want to be sure the color matches that of your newly bleached teeth.
• To avoid the technicolor effect, tooth-colored restorations will likely need replacement after bleaching.
• Recessed gums often reveal their yellowish root surfaces at the gum line. That yellow color has proven difficult to bleach.
• Pregnant or nursing women are advised to avoid teeth whitening. The potential impact of swallowed bleach on the fetus or baby is not yet known.

Home Recipe for Teeth Whitening

Never underestimate the value of a smile. It can communicate happiness and health, and a smile can be a beauty-focal point of your face. Haven’t you noticed perfect smiles on the red carpet? It’s those straight, white teeth, and red lipsticks that are begging paparazzi to keep coming back for more Lindsay Lohan and Britney Spears. (Or perhaps it’s more than just their smiles =) ).

The craze for that perfect smile has flooded Hollywood and has leaked into our everyday life. We are bombarded with television infomercials promising white-out shade teeth in “just 30 minutes a day.” Even your local drug store is lined with teeth whitening kits promising “10 shades lighter in just five minutes a day.” However, little is shade about the pricing of these services: a bleaching session with a dentist can cost upwards of $400, while strips and trays are priced at ~$40 and requires continual usage. Is there a home recipe for teeth whitening that can accomplish the same task for cheaper?

Quick research on the web will suggest that hydrogen peroxide is a good agent for teeth whitening. However, dentists have reported that the over-the-counter peroxide is not the same ingredient as ones found in bleaching gel. Bleaching gel contains carbamide peroxide as well as some concentrated hydrogen peroxide. If you want to whiten your teeth but would rather not pay for the strips or professional service, try the home recipe for teeth whitening : Take one teaspoon of baking soda and some drops of hydrogen peroxide (no more than 3%). Mix these ingredients and form a paste. Brush your teeth with this paste. To prevent decay, you must brush your teeth again with a fluoride toothpaste . Repeat once a week or two. You’ll love the result!

If the recipe works so well, why use it only once a week? Baking soda is abrasive and can damage your gum and can permanently damage the enamel of your teeth. Baking soda can dissolve orthodontic glue. Do not use this method if you have braces or a permanent retainer. Please do not go out and buy concentrated hydrogen peroxide in attempt to whiten your teeth. Hydrogen peroxide is a strong oxidizer and can cause damage at a concentration higher than recommended (3%). Beware, using strong hydrogen peroxide for rinsing may result in abnormal hair growth, so keep an eye out for a hairy tongue. In addition to the hairy tongue, you may even subject yourself to hydrogen peroxide burns. (Just stick with the 3% hydrogen peroxide).

I’m sure you’ve heard about using lemon juice to whiten teeth. My advice is to not do it. Lemon juice is an acid and with the nature of all acid, it can be damaging, especially to tooth enamel. Initially, you will notice “whiter” teeth; this is because the lemon juice causes the teeth to lose calcium (has an off-white color). Once the calcium is gone, your teeth are more susceptible to decay.

If the self assembly, home kit is too much of a hassle, try professional bleaching products. These products often contain low sensitivity formulas and a higher percentage(~20%) of carbamide peroxide, the form of peroxide that dentist use. Check out products by the SmileSalon at this link: The smile salon. The results can be drastic (several shades) in one sitting. However, if you have a few weeks to spare, the above home recipe for teeth whitening should work.

Happy brushing!