Peroxide-based tooth whiteners.
- Do they harm or damage dental work or dental materials? What are the effects of bleaching compounds on white fillings, silver fillings, porcelain restorations.
Does whitening your teeth damage your dental work?
If tooth-bleaching agents are strong enough to lighten your teeth, you might wonder if they will damage the dental work you have.
Studies have determined that many types of dental materials are affected by peroxide-base whiteners. But it's also important to point out that documenting an effect doesn't necessarily mean that it's a clinically significant (problematic) one.
We've chosen what we feel are the major issues and concerns in regard to this topic and discuss them below.
Using peroxide-whitening technique is time-tested.
When it comes to this subject, it needs to be pointed out that most of the products and methods currently in use have been around for the last 20 years and more. And that type of time span provides a lot of opportunity for problems to have been discovered and investigated.
At this point in time the evidence seems to be that most issues are either well known or else don't pose a great risk or concern. (Heymann 2005) [reference sources]
Harmful effects of peroxide whiteners on dental restorations and materials.
a) White dental fillings.
i) Physical damage.
Some, but not all, studies evaluating the effects of bleaching agents on dental composite restorations (white fillings) have reported effects.
- Peroxide-based whiteners (concentration 3.6% and greater) may increase the surface roughness of white fillings at a microscopic level.
- They may also affect their hardness and cause increased microleakage.
A change in surface texture could affect the ease with which dental plaque is able to adhere to a tooth, thus leading to (secondary) tooth decay formation. Or if the roughened filling is in the region of the tooth's gum line, maintaining gum health could be more difficult.
Decreased hardness or increased microleakage would tend to compromise a filling's integrity (its ability to withstand chewing forces or penetration by oral bacteria).
At this point in time it seems the clinical significance of these effects is of just minor concern, if even that.
ii) Bond strength of new fillings.
Placing dental composite fillings too soon after whitening treatments have been performed has been shown to inhibit the strength of the bond created at the tooth-filling interface. (A decrease on the order of 25%.)
The problem is thought to stem from the presence of oxygen generated during the bleaching process that still remains within the tooth's hard tissues. (Haywood 2009)
Studies have shown that a wait period of 2 to 3 weeks provides enough time for the oxygen to dissipate. Then at this point, a normal-strength bond can be created.
iii) Affects on color.
It's possible for peroxide whiteners to have a lightening effect on the color of existing white fillings (dental composite restorations).
- If this effect does take place, it's only marginal.
- This is the exception, not the rule.
In the vast majority of cases, bleaching treatments will have no effect on the color of the person's white fillings.
iv) Other white dental materials.
The white dental plastic methylmethacrylate may stain orange when it's exposed to peroxide whiteners.
While once more prevalent in dentistry, nowadays the only common use of this plastic is in the making of temporary dental crowns.
b) "Silver" (amalgam) fillings.
i) Mercury leakage.
Laboratory studies have shown that exposing dental amalgam (the metal used to make "silver" dental fillings) to peroxide triggers the release of mercury and silver.
- 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.)
This process may be more likely to take place with newer restorations (it may be inhibited by dental biofilms that have built up as a coating on older ones). And for this reason, your dentist may want to delay starting your whitening treatments if a number of new amalgam restorations have recently been placed.
ii) Tarnish / Greening.
Amalgam fillings have the potential to tarnish, or possibly develop a green tint, when subjected to whitening treatments. This effect is more likely to take place when higher peroxide concentrations and longer treatment times are involved.
- For this reason, silver fillings in teeth that hold an especially prominent position in a person's smile are sometimes replaced with white ones before their bleaching treatments are begun.
- However, it's commonplace that teeth that have silver fillings are exposed to peroxide whiteners, typically without significant incident.
C) Dental cements.
Studies have shown that dental cements may be eroded or stained by peroxide whiteners. However the clinical importance of this effect has yet to be demonstrated.
D) Porcelain restorations.
The over 25 years of history of exposing porcelain-surfaced restorations to peroxide whiteners (like those used with tray-based technique) has not shown that this activity results in any clinically significant damage.
In most cases the most significant clinical issue encountered is that a person's natural teeth will lighten due to their treatments but not their porcelain restorations.
This can either be a detriment or an asset.
- If performing whitening treatments have created a color mismatch (porcelain restoration vs. natural teeth), the only solution is to replace the restorations so their color 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.
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