Category Archives: Tooth Whitening

“I understand how bleach works.  I have even picked the method I think I would prefer.  How do I know if it is going to work for me? ”

In a previous post, “Whiter Teeth! (Part 2)”, we explored three methods for applying bleach to whiten teeth.  In our last post, “Whiter Teeth! (Part 4)”, we investigated objective and reliable scientific research and concluded that at-home tray bleaching works best.

Understandably, many clients wonder if bleaching results might vary from one person to the next.  They often ask us how well it will work specifically for them.  In this post we will review the factors that will determine if you are a good candidate for tooth whitening.

The images to the right are un-retouched “Before and After” photographs taken of the same patient (using the same camera, flash, exposure settings, and distance) for a fair and unbiased comparison.  Did the tooth whitening work?  Absolutely.  Was the patient happy with the results?  Ecstatic!  (“My teeth have never been this white,” she claims. “Ever!”)  Is everything “perfect” now?  Well…   The “Expectations”  image is identical to the “After” image.  I added arrows to point out areas where pre-existing factors created minor (but predictable) limitations in the outcome.

Let’s learn how to recognize those factors.

Initial tooth color

While all teeth are generally ivory in color, everyone is born with an innate tint that ranges from yellowish-brown to greenish-grey.  It turns out that the yellowish-brown color is more responsive to tooth bleaching than the green-grey color.  Teeth that appear to have a gray stripe through the middle of the tooth can be particularly stubborn when it comes to whiten. (The “Before” photograph of our sample case shows an example of teeth with an overall grayish color.)

Tooth color and age are also directly linked. With wear and stain accumulation, teeth often start to take on a darker cast.  With age, the yellow colors can evolve into a darker brownish hue, and those are harder to eliminate.

Several years ago, tetracycline was frequently prescribed to help children battle ear infections.  Later it was learned that tetracycline usage during tooth formation could produce horizontal brownish- grayish stripes of discoloration which are very difficult to remove. Excessive consumption of fluoride can cause a splotchy enamel appearance called fluorosis.  Although medical doctors now avoid prescribing these medicines during tooth development, millions of people have already developed darkened teeth caused by prescribed medications.  (While the teeth in our sample case became significantly whiter, the “Expectations” photo reveals a mild lingering horizontal grayish “stripe”–at the blue arrow—the result of internal tetracycline “staining” acquired from childhood antibiotic treatment decades earlier.)

Of course, the starting color of your teeth matters.   You probably wouldn’t be surprised to learn that darker teeth may require extra effort to whiten.   Just because the bleaching results are less effective with darker colors does NOT mean that they are ineffective.  Repeated procedures over an extended period of time are sometimes required.

Roots and Restorations

Although tooth enamel responds well to tooth whitening solutions, root surfaces don’t.  (The yellow arrow points out just one of several areas where this patient had experienced previous gum recession which had exposed her root surfaces.  Understandably, those areas did not change color during the bleaching treatment.)

Tooth-colored restorations utilize acrylic or porcelain materials that are also unaffected bleaching solutions. If you have fillings or crowns that currently match your tooth color, they won’t after tooth whitening.  (Notice how the red arrows identify several porcelain crowns that didn’t change color at all.)  At Snow Dental Care, we avoid using porcelain crowns with unsightly metal edges.  If you happen to have a crown with an exposed metal band from treatment in a previous office, however, you probably won’t be surprised to hear that the bleaching treatment cannot help to improve that situation either.

Tooth Translucency

Translucency is an optical property that describes how scattered light can pass through a material.   Unlike the transparency of clear water or a pane of glass (that allows all light to pass directly through unimpeded), translucency imparts a white hazy appearance to a material that deflects and reflects a portion of the light that passes through it.  When it comes to teeth, this genetically-determined trait becomes more pronounced over time.  As tooth wear and optical changes develop with age, translucency increases.  Thinning translucent teeth are less-responsive to bleaching.

Consumption

The cliché “you are what you eat” certainly applies to the color of your teeth.  If you enjoy coffee, tea, red wine, or other highly-pigmented foods and beverages, you can expect the dark, colored molecules to become trapped in the microscopic spaces between the crystalline columns that make up your enamel.  The same is true for smoking.  The use of tobacco can leave dark deposits which slowly penetrate the tooth structure to cause internal intrinsic discoloration.

Common Sense Conclusions

While all bleaching methods “work” to one degree of another, at-home tray bleaching works best to achieve the brightest and longest-lasting results in the least amount of time for the least total financial investment.  This method also has the lowest potential for creating unwanted tooth sensitivity side effects.

Although all tooth enamel predictably becomes lighter and whiter in color after tooth bleach application, patients with exposed roots or existing dental restorations should expect those areas NOT to change color during the tooth whitening process.  Restoration replacement is sometime required to achieve a uniformly whiter result.

Similarly, patients with grayish teeth will find them to be less responsive to the tooth whitening procedures that patients with yellow-tinged teeth.   In these circumstances, additional repeated procedures over an extended period of time are sometimes required to achieve the desired effect.

While tooth bleaching affects the color of natural tooth structure, it does not alter the appearance of the shape, proportion, or alignment of teeth.  For patients who wish to achieve lighter results or mask problems that cannot be addressed with bleaching treatment alone, they may wish to consider additional dental procedures (such as Invisalign, bonding, or porcelain veneers) to enhance the outcome.

Copyright © 2013  Stephen R. Snow, DDS

“How do the results of the different methods of bleaching stack up when they are compared?  What facts are being considered?  How can you know which way is ‘the best’?”

In a previous post, “Whiter Teeth! (Part 2)”, we introduced three procedure strategies for applying bleach to whiten teeth:

• in-office, power bleaching
• at-home, dentist-supervised tray bleaching
• over-the-counter, do-it-yourself bleaching

In our last post, “Whiter Teeth! (Part 3)”, we discussed the importance of analyzing peer-reviewed scientific research before recommending any procedure or using any material when treating our patients.  We want to rely on valid scientific evidence—and not biased opinion—to make objective decisions about what is best for our patients.  We quoted two dependable resources [1] [2] that had concluded that at-home, dentist-supervised tray bleaching is best.[3]

Does that mean that in-office power bleaching is just a hoax?  Does that mean that whitening strips from the local pharmacy don’t work?  Of course not!  But they don’t work as well as at-home tray bleaching.

How do we know? Let’s take an objective approach by listing some scientific facts about getting your teeth whiter.  (If you just want a summary conclusion, feel free to jump to the bottom.)

Tooth Whitening Facts

• Each tooth has a maximum whiteness level that it can achieve.  It cannot be whitened beyond that maximum level no matter what material or technique is used for bleaching.[4] [5]
• Each tooth has a maximum rate at which the whitening can progress.  Once that rate is reached, higher concentrations of bleaching solutions make no difference in the speed of whitening process.[6] [7] [8] 
• The eventual whitening result achieved is determined by the properties of each tooth—not the product used.[5] [7] [9] [10]
• Tooth sensitivity is the most common side effect of bleaching.[3] [5] [11]

Bleaching Material Facts

• Although the exact concerntrations from each manufacturer vary a bit, Hydrogen Peroxide (35%) is typically used for in office bleaching while Carbamide Peroxide (10%) is typically used for at-home tray bleaching.
• Tooth sensitivity during treatment is more common with higher concentrations of peroxide bleaching solution.[3] [10]
  

In-Office Bleaching Facts

• In-office whitening techniques typically utilize a prop to hold the mouth open and isolate the teeth.  This process temporarily dries out the teeth.  Teeth appear significantly whiter when they are dehydrated.  Unfortunately, that whiter appearance reverses completely in a matter of just a few days—sometimes within a few hours—when the teeth become wet with saliva again. [4] [12]
• In-office bleaching procedures usually utilize a bright blue light to “activate” the bleach solution that has been painted on the teeth.  Several unbiased scientific experiments have compared what happens when half the teeth are whitened with the use of light activation while the other half of the teeth in the same patients were treated without light activation.  The light made no difference. [8] [13] [14]   Although the teeth were much whiter immediately after treatment, the effect is due to dehydration [15]—not light activation—and reverses in just a matter of days.[11]
• The results from one in-office bleaching treatment are not as white or as long lasting as the outcome from at-home tray bleaching.[4]  Satisfaction surveys have shown that patients require 3-4 in-office treatments to achieve the same whitening effect as at-home tray procedures.[11] [16] 
• Manufacturers of in-office light-activated power bleaching systems often recommend the use of additional at-home tray whitening to “complete the bleaching process”.[11] 

Over-the-counter (OTC) Bleaching Facts

• OTC whitening strips use a “one-size-fits-all” rectangular membrane loaded with bleaching solution.  The membrane is pressed against and adapted to the teeth. [3]
• Since the OTC strips are not custom fit for each patient, they can inadvertently be  positioned too far over the gums resulting in increased irritation and sensitivity.
• Since the OTC strips are arbitrary in length, it can sometimes be difficult for patients to achieve a predictable and uniform whitening effect on their side teeth.[4]

Bleaching Comparison Facts

• 3 in-office applications of 38% Hydrogen Peroxide achieved the same result as 1 week of 10% carbamide peroxide nightly or 16 daily applications of 5.3% hydrogen peroxide on OTC whitening strips.[17]
• Attempting to use higher concentrations of bleaching solution to shorten the time required for tooth whitening makes no difference in the final outcome.[3] [4] [7]
• Attempting to use higher concentrations of bleaching solution can, however, increase tooth sensitivity and/or rebound (a reversal of the whitening effect) [18]

Common Sense Conclusions

In-office power bleaching works.  Unfortunately, a significant part of the initial whitening effect is due to temporary tooth dehydration—which rapidly reverses as the teeth become wet again with saliva.  The light used has been shown to provide no long-term enhancement to the whitening outcome.  The procedure costs more, must be repeated more, and has a higher risk of tooth sensitivity than at-home tray techniques. Manufacturers even recommend the use of additional at-home tray procedures anyway.

Over-the-counter do-it-yourself bleaching works.  Unfortunately, the lower concentration of bleach often takes much more time and many more treatment repetitions to achieve a desired result when compared to at-home tray techniques.  The one-size-fits-all strips are more prone to gum sensitivity and may be more difficult for some patients to get a uniform whitening for their side teeth.

At-home tray bleaching works best.  It creates the longest-lasting tooth whitening results in the least amount of time.  Although some patients experience tooth sensitivity during treatment, the custom-fitted tray, solution (carbamide peroxide), and  lower concentration of bleach (~10%) all reduce that possibility.

It would be great if tooth whitening worked perfectly for every tooth with every patient.  As you might expect, however, some teeth don’t respond as well as others.  We will investigate how to predict the outcome in our next post: “Whiter Teeth! (Part 5)”.  Stay tuned. 

Copyright © 2013  Stephen R. Snow, DDS

(I know you count on me to evaluate scientific study on your behalf and to apply relevant advances and discoveries in the recommendations we make and the treatment we deliver at Snow Dental Care.  If you still want to dig a little deeper on your own about tooth bleaching, I have included references—and even links, when possible—for the scientific facts included here so you can investigate more if you’d like.)