Do peroxide-based tooth whiteners harm or damage dental work?

- What's the effect of teeth-bleaching treatments on white fillings (dental composite), silver fillings (amalgam), porcelain restorations (bridges, crowns and veneers) and creating bonded restorations?

Will performing whitening treatments damage your dental work?

If peroxide tooth-bleaching agents are strong enough to lighten your teeth, you might wonder what effect they may have on your dental restorations.

It's easy enough to suggest that most people don't notice any effects.

Most of the whiteners and bleaching techniques currently in use have been around for almost 30 years. (The boom in at-home whitening began in the early 1990s. And the history of dentists providing in-office treatments is even longer than that.)

And during that time span, it seems reasonable to estimate that hundreds of millions of individual teeth and their restorations have been exposed to whiteners and the bleaching process. And from that pool, we can state that very few accounts of problems or damage caused to existing dental work have been reported. (As evidenced by a lack of cases documented in published dental literature.)

So generally, it seems that most people who undergo a whitening process (either at home or in their dentist's office) don't experience any noticeable complications with their existing dental work.

But that's not to say that exposing dental work to peroxide whiteners is totally benign.

In reality, there are a plethora of studies that have documented how a person's existing dental restorations can be affected by the peroxide-based whiteners used to bleach teeth. So, the issue then becomes to what level of clinical significance do these events arise?

That's what we discuss on this page. We present what we feel are the major issues and concerns associated with exposing dental restorations to the teeth-whitening process (both at-home and in-office techniques), specifically in regard to:

 

Consulting with your dentist beforehand makes a great idea.

As a last point, we'll mention that with some of the issues discussed below it may be difficult for a layperson to understand exactly which ones apply to their situation.

For that reason, if you have any dental work at all that will be exposed to a whitening process, it's always best to consult with your dentist beforehand, so they can confirm that your potential for complications seems minimal.


Harmful effects of peroxide tooth whiteners on dental restorations.

a) Dental composite -

FYI: Composite resin is the type of dental restorative that's most frequently used to create tooth-colored fillings.

Overview.

Some level of deterioration probably takes place ...

A number of studies have investigated the effect of peroxide-based whiteners on dental composite restorations. These evaluations have looked for changes in restoration color, surface hardness, surface roughness, staining susceptibility, restoration leakage and bond strength.

Some studies, but not all, have reported finding measurable effects. (We discuss several of them just below.)

But in regard to their clinical significance ...

We think it's safe to say that the general consensus in the dental community is one where some effects apparently do take place. But studies have not shown that they rise to a level where they are of significant clinical concern. (El-Murr)

As evidence in support of this opinion, the simple fact that peroxide-based whiteners have been used extensively over the last 30 years by the general population, and no wide-spread clinical issues have yet been observed with composite fillings, and teeth bleaching continues to be promoted by the dental community as a whole, seems to be a confirmation of this point.

Section references - El-Murr

Issues of potential concern.

1) Composite hardness.

There have been conflicting reports about the effect of peroxide bleaching agents on composite resin hardness. Some researchers have documented that a decrease in both surface and/or internal microhardness does occur. Others have not identified this change.

An obvious concern related to this issue would be one of restoration strength (like its ability to withstand chewing forces). But just as important, even minor chipping at the edges of a weakened restoration could allow leakage of bacteria and contaminants, which would also ultimately lead to filling failure.

The evidence is inconclusive.
The clinical relevance of what may take place remains unclear, and therefore requires further investigation. But considering the long history of peroxide teeth bleaching without evidence of an increase in the rate of composite restoration failure suggests that this issue is probably of limited concern.

Section references - El-Murr

2) Composite surface roughness.

Some studies have documented that even low peroxide (at-home use) whiteners increase the surface roughness of dental composite restorations.

Questionable clinical relevance.

One study (Wattanapayungkul) did consider the level of surface change that took place to be significant. But also determined that the degree of roughness (which was less than 0.2 microns crest-to-valley) was not great enough to aid with plaque formation and retention, and therefore was considered clinically insignificant.

In the case that a composite restoration is determined to have significant roughness, its surface can be polished.

Section references - El-Murr, Wattanapayungkul

3) Composite restoration microleakage.

For this discussion, microleakage refers to a process where oral contaminants are able to seep past the bond that's been created between a dental composite restoration and its neighboring tooth structure. Microleakage can result in recurrent tooth decay.

At this point in time, it's generally considered that exposure to peroxide tooth whiteners does not cause microleakage of composite restorations.

Section references - El-Murr

4) Composite staining.

A study by Yu determined that dental composite restorations exposed to peroxide whiteners stained more easily than unbleached ones. Possibly this effect is related to the increase in surface roughness that takes place during the bleaching process (discussed above).

Possible solutions.
A dentist may be able to polish off restoration surface staining. In some cases, further whitening treatments may remove external staining too.

Section references - Yu

5) Composite color stability.

Usually, no color change takes place ...

It's generally considered that bleaching agents won't provide a lightening effect for white fillings (dental composite resin restorations, the most common type of white filling). (Villalta)

And as such, the usual expectation is that the patient will need to have their existing fillings replaced after their whitening treatments have been completed, so to match their smile's new shade.

If a color change occurs ...
Some studies have found that the color of some types of composite resins is affected by exposure to professional-grade or even at-home whiteners. (Hubbezoglu) But even if this (unpredictable) effect does take place, restoration replacement will still likely be required to create the perfect color match.

Section references - Villalta, Hubbezoglu


b) Bond strength of new restorations.

This issue is of clinical importance.

It's well documented that placing bonded restorations (white fillings, veneers, etc...) too soon after whitening treatments have been performed has the potential to significantly inhibit the strength of the bond created at the tooth-restoration interface.

This problem is thought to stem from the presence of oxygen generated during the bleaching process that still remains within the tooth's hard tissues.

The timing that's needed.

Studies have shown that a waiting period of at least 2 weeks is needed for the accumulated oxygen to dissipate. Then at that point, a normal-strength bond can be created.

To reiterate, the general practice is that all of your bleaching activities must be ceased 2 to 3 weeks before a new bonded restoration is placed. However, your dentist may have their own time table that they think is important to abide by, so you should check with them for specific instructions.

Section references - Metz


c) Other types of white-colored dental restoratives.

Besides dental composite, there are other materials that a dentist might use to create a "white filling" for a patient. These include "compomer" (polyacid-modified composite resin), "ormocer" (organically modified ceramic), glass-ionomer and resin-modified glass-ionomer restoratives.

And all of the same potential issues and concerns as discussed with dental composite above would generally apply to these materials too.

These are less-used restoratives.

By far, dental composite has been, and continues to be, the most-used material for creating white fillings. And due to their much more limited use, we've decided that a thorough discussion covering the effects of bleaching agents on other classes of restoratives lies beyond the scope of this page.

Additional materials and applications.

The white dental plastic methyl methacrylate may stain orange when it's exposed to peroxide whiteners. The most common use for this plastic is making temporary dental crowns.


d) Amalgam ("silver") fillings.

Overview.

Researchers investigating the effect of peroxide tooth whiteners on dental amalgam have looked for changes in restoration microhardness and surface roughness. And while some minor effects have been identified, it's generally considered that they lie within a clinically acceptable range. (El-Murr)

Beyond those issues, some effects specific to amalgam may take place that suggest that the best-practices discussed below should be followed when this type of restoration will receive exposure to a peroxide bleaching agent.

Section references - El-Murr

Notable issues.

1) Mercury leakage.

A laboratory study (Al-Salehi) demonstrated that exposing dental amalgam (the metal used to make "silver" dental fillings) to peroxide whiteners triggers the release of mercury and other metal ions.

  • This effect can take place for up to 80 hours after the exposure.
  • The concentration of the whitener plays a role in the rate at which this reaction occurs. (Higher concentrations cause more of an effect.)

 

Studies haven't shown that the level of mercury released exceeds World Health Organization limits (so the effect is not considered a health hazard). (El-Murr)

Treatment planning.
This process may be more likely to take place with newer restorations (it may be inhibited by dental biofilms that build up). And for this reason, your dentist may want to delay initiating your whitening treatments if a number of new amalgam restorations have recently been placed.

Section references - El-Murr, Al-Salehi

2) Tarnish / Greening.

Amalgam fillings have the potential to tarnish, or possibly develop a green tint, when exposed to teeth whiteners. This effect is more likely to take place when higher peroxide concentrations and longer treatment times are involved.

  • For this reason, silver fillings placed in teeth that hold an especially prominent position in a person's smile are sometimes replaced with white ones before bleaching treatments are begun.
  • However, the norm is that teeth that have silver fillings undergo their whitening process without significant incident.

Obviously, your dentist's input would be a valuable asset on this issue.


e) Porcelain restorations (bridges, crowns, veneers, etc...).

Overview.

Studies have shown that exposure to peroxide tooth-bleaching agents can affect the surface roughness and microhardness of some dental porcelains.

In our reading of several of these studies, it seems that this concern is most associated with "feldspathic" porcelain. (A type of ceramic that's still in common/frequent use in dentistry but is increasingly being supplanted by more modern ones.) And the level of effect may correlate with the type of final surface treatment (glazing) the restoration has received.

A prudent approach to take when porcelain dental work is involved.

Two significant concerns that are associated with this issue are:

  • If significant restoration damage or harm results (discussed below), the time and expense involved with replacing porcelain restorations can be considerable.
  • It may be difficult, if possible at all, for even a dental professional to determine the nature (material, fabrication method) of some porcelain restorations.

 

As such, a best-practice is to avoid bleaching ceramic restorations, especially those on front teeth. After consultation with your dentist, it may be determined that concerns are unwarranted, or are just limited, and bleaching plans can be made.

Section references - El-Murr

Issues of concern.

1) Surface roughness / Microhardness

Specifics.

In a review of this subject in 2011, El-Murr cites studies that suggest that exposing some types of porcelain-surfaced restorations to peroxide bleaching agents can result in increased surface roughness. (Specifically feldspathic porcelain restorations whose final glaze has been applied in a specific fashion. Traditionally, this type of restoration has been commonplace in dentistry.)

The problem.

The concern with this issue is that an increase in surface roughness may allow increased plaque retention (which could affect the health of the tooth's surrounding gum tissue, or possibly promote decay on the tooth or its adjacent natural teeth). Possibly the color ("whiteness") of the porcelain may be affected too.

The review also mentions that some studies have reported changes in porcelain microhardness after being exposed to peroxide whiteners.

The paper suggests that it's wisest to avoid bleaching ceramic restorations, especially those placed on front teeth. We would point out that this type of specific isolation would be difficult, if not impossible, to accomplish with most at-home whitening methods.

Section references - El-Murr

Additional studies.

In investigating this issue further, we've found more recent studies (both by Torabi, 2014) that confirm both issues (surface roughness and microhardness changes do occur with feldspathic porcelain surfaces when exposed to peroxide whiteners).

Both studies in their discussions state that nothing (no precautions other than avoidance) can "preserve these materials from adverse effects of bleaching agents."

Section references - Torabi, Torabi

The needed plan when any type of porcelain restoration is involved.

In light of this information, if you have any porcelain restorations that will receive exposure to the bleaching agent, at a minimum you need to discuss this issue with your dentist beforehand. Many porcelain dental restorations are not made using feldspathic porcelain, possibly they can determine what material has been used for yours.

During that consultation, you must discuss what plan will be in place if the effects of your bleaching treatments are found to be detrimental to your restorations so there are no surprises. Replacing the restorations may be needed. In theory, it may be possible for your dentist to re-polish roughened porcelain restorations.

2) Bleaching effects on porcelain color.

In the case where it's deemed appropriate to involve ceramic restorations in whitening activities, the person needs to understand that the color of their ceramic restorations cannot be expected to change.

This lack of effect might either be a detriment or an asset.

  • If performing whitening treatments have created a color mismatch between existing porcelain restorations and natural teeth, the only solution is to replace the restorations so their color then matches.
  • As a reverse approach, in some cases whitening treatments are used to lighten natural teeth that have darkened over the years back to their lighter original shade. That way they once again match the color of their adjacent porcelain restorations that were placed back at that time.

 

Porcelain veneers can be the exception.

The exception to the rule about porcelain restorations not changing color is porcelain veneers. Whitening treatments may lighten them. This page describes why this effect takes place.

Consequences.

Not understanding when your porcelain restorations will not, or possibly may, lighten can prove to be a costly affair if it leads to a need for their replacement. This issue is another prime reason why it always makes sense to mention your whitening plans to your dentist before you initiate them.

 
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 Page references sources: 

All reference sources for topic Tray-based Teeth Whitening.

Al-Salehi SK, et al. The effect of hydrogen peroxide concentration on metal ion release from dental amalgam.

El-Murr J, et al. Effects of external bleaching on restorative materials: A review.

Hubbezoglu I, et al. Effect of bleaching on color change and refractive index of dental composite resins.

Metz MJ, et al. Clinical evaluation of 15% carbamide peroxide on the surface microhardness and shear bond strength of human enamel.

Villalta P, et al. Effects of staining and bleaching on color change of dental composite
resins.

Torabi K, et al. Evaluation of the effect of a home-bleaching agent on the surface characteristics of indirect esthetic restorative materials: part I--roughness.

Torabi K, et al. Evaluation of the effect of a home bleaching agent on surface characteristics of indirect esthetic restorative materials--part II microhardness.

Wattanapayungkul P, et al. The effect of home bleaching agents on the surface roughness of tooth-colored restoratives with time.

Yu H, et al. Effects of carbamide peroxide on the staining susceptibility of tooth-colored
restorative materials.

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