Crest Whitestrips® – Can you use additional kits? | How often? | How many? | How soon? | How about for touch-ups?
After you’ve used one package of WhiteStrips®, can you use more?
Once you have finished your initial kit of whitening strips, and especially if the results weren’t quite as dynamic as you had hoped, you may wonder – Can I use additional boxes? How many?
Or after completing your treatments, and you were happy with the original results but now some fading has occurred, you may wonder – How soon can you perform touch-up treatments? How many whitening strips should you use? How many times per year?
There are issues that must be considered.
Usually, the answer is yes. You can use additional whitening strips or even boxes of strips but there are issues that should be considered and general guidelines followed.
This page discusses these factors and provides examples from published research about what was found to be the outcome with test subjects (advantages vs. complications) when extended treatment was used. And what a major manufacturer says about using additional packages of their products (how many boxes, how many times).
What’s the bottom line about using additional whitening strips or strip kits?
With some exceptions, it’s usually reasonable enough to use a second box of WhiteStrips®, even immediately following your first one. But some level of consultation with your dentist is indicated if you’re considering further use beyond that.
There are fewer concerns with performing touch-up work as opposed to extended treatment. With this application, it’s usually more of a question of how many (how few) individual strips may be needed, and how often this kind of maintenance work will need to be performed (months/years).
How many boxes of Whitestrips® are permissible?
A) Extended treatment.
How many boxes of whitening strips can you use?
The official word from Crest® about WhiteStrips®.
What we see stated on their website.
- “You can use one pack right after another.” – Meaning two boxes of strips (as in a “twin pack” of WhiteStrips® as they are sometimes sold).
- The same paragraph then states that they “recommend using Whitestrips twice per year.”
(We’re assuming this frequency is based on the claim found on the same page that states treatment results can last 6 months to a year.)
But really, despite their spelling it out with those statements we still had questions.
We didn’t understand whether …
- You can use two back-to-back kits of strips twice a year? (For a total of 4 packages.)
- Or if you use two packs back-to-back, do you need to wait 12 months before performing treatments again? (For a total of only 2 kits of strips per year.)
What Crest® customer support stated.
Based on their email reply to us (January 2020), we can report that they generally recommend the latter regimen (only using two packages of strips per year), and that recommendation only applies to some (although most) WhiteStrips® products. With one product (Supreme), they only recommend using it once (a single package) per year.
Specific details found in their email.
How many Whitestrips® kits can you use per year?
Per their communication, using two kits per year (either back-to-back or separated by a period of time) is considered permissible when using their 3D White Classic Vivid, Glamorous White, 1 Hour Express, Gentle Routine, Shimmer White, Professional Effects, or 3D White Whitestrips with Light products.
When it comes to their 3D White Supreme Flexfit Whitestrips (a product that has a comparatively higher concentration hydrogen peroxide whitener), they stated that only one kit should be used per year.
Details about using more than one package.
Their email stated that you can mix and match different types of kits, like using one 3D White Classic Vivid and one Glamorous White, or just two 3D White Classic Vivid.
More interestingly, one of their kit combination examples was specifically stated as “one 3D White Supreme Flexfit kit + one other 3D White kit.” So a package of the higher peroxide concentration product can be used in conjunction with one “regular” kit, for a total of two per year. But not two of the 3D White Supreme Flexfit product.
When might you use more than one box of whitening strips?
Using two packages consecutively.
The only reason to consider immediately using a second kit is if the first one didn’t produce results that were as dynamic as you were hoping. That is the single indication.
This is the type of situation that might present itself if your teeth had a significant level of discoloration initially. (It’s well known that some types of tooth staining won’t respond as quickly or fully to whitening treatments as others.)
But even then, using a second box of strips, while permissible under the guidelines of the product, may not make an appropriate choice. (We discuss this issue in our Dentist Supervision section below.)
How about two kits per year, some months apart?
Corresponding with Crest’s® claims mentioned above, research suggests that the results achieved via whitening strips treatments can be expected to last 6 to 12 months (possibly even longer, our “Touch-up” section explains.
So choosing to use two complete kits per year might fall under the category of either improving your results or touching them up, or both.
An example of when using multiple boxes of strips would not be appropriate.
An obvious exception for multi-pack use would be the situation where the user has experienced substantial side effects with their first kit that were either very difficult to resolve or possibly even continue.
In these cases, the use of a second kit is contraindicated. And exactly what does constitute an appropriate whitening method for the person should be reevaluated.
Can there be exceptions to how many packages of WhiteStrips® can be used?
Yes, some people’s teeth might be (appropriately) treated using multiple consecutive boxes of strips. But in considering this idea, the person enters into a realm where they probably don’t have the knowledge or expertise to determine exactly what does constitute an appropriate exception. And with some cases, the issue of end-user whitener abuse might be a valid concern.
So generally, it’s hard for us to suggest that exceeding a manufacturer’s recommendation on your own ever makes a good idea. Especially considering how easy it is to get the level of oversight that’s really indicated for extended use.
“Supervised” at-home use.
The most appropriate (and prudent) use of multiple boxes of white strips involves the situation where you seek your dentist’s oversight. Formally, this might involve little more than mentioning to them that you have used the recommended number of packages and would like to consider using more, and just letting them take it from there.
As your dentist, and especially if you’ve consulted with them before beginning any treatments, they’ll know what your initial conditions were. And already have an opinion about what originally caused the discoloration of your teeth, which can be an important factor in understanding the extent of treatments that may be needed to resolve it.
And from your reporting, they’ll have an idea of what level of results have been gained, using what concentration (peroxide level) and what number of whitening strip kits. And based on their knowledge and experience with other patients, be able to draw a conclusion about how realistic it is that further treatments will produce an added effect.
Just as important, as you enter into the territory of extended use (on your own at home) and its realm where side effects may become an increasing issue, you’ll have someone to consult if needed.
If you haven’t already consulted with your dentist …
This is still the person that needs to be brought into the loop about your continuing on with further treatments. No one knows more about the issue of whitening your teeth, and you and your teeth in particular. It’s important to take advantage of this resource.
Even without complete background information, your dentist will still be able to form a valid enough estimate about the potential for achieving a further whitening effect by using additional boxes. And, of course, having them already in the loop if side effects need to be managed is an important asset.
What can be expected when using additional packs of whitening strips?
Some examples of extended use from research –
Title: Effects of duration of whitening strip treatment on tooth color: A randomized, placebo-controlled clinical trial.
This study evaluated the use of Crest Whitestrips® (6% hydrogen peroxide), twice daily, 30 minutes each application, over 2, 4, and 6-week periods. Per the instructions of this product, this equates to using a 2nd and 3rd kit consecutively.
- The study found that the greatest level of effect was gained during the first 2-week period (equating to the use of one kit). But continued use out to the 4 and 6-week points did produce a further effect (reduction in yellowness, increase in lightness).
- 35% of the subjects did experience some level of side effects. Most symptoms were noticed during the initial use of the strips (median onset at day 3). No subject’s treatment was modified or discontinued due to side effects.
What we feel this study points out about using additional boxes of strips.
This study did find that extended treatment did produce better whitening results. But in their paper, the authors specifically pointed out this may have been due to the comparatively dark shade of their subjects’ teeth initially.
It discussed that in comparison, people whose teeth are comparatively lighter in shade initially typically experience a whitening plateau (a point where the continued use of bleaching products produces no further effect) and reach this point relatively rapidly (like within the number of kits recommended by the manufacturer). (We discuss this issue further below.)
So for many people, the use of additional kits may hold little potential for added whitening, while placing them at the continued potential for experiencing complications. Objectively being able to determine when this plateau effect has occurred (and therefore the point where further treatment will be fruitless) is a part of what having your dentist’s supervision over your activities can offer.
We’ll also point out that while side effects were not found to be a significant problem for the subjects, this was not a foregone conclusion. And due to the uncertainty of experiencing complications, all of the subjects had supervision during the weeks of their treatment.
Title: Placebo-controlled, 6-week clinical trial on the safety and efficacy of a low-gel, 14% hydrogen peroxide whitening strip.
This study was somewhat similar in nature to the Swift one above. A six-week extended-use period was evaluated. However, in this study, a 14% (Crest Whitestrips® Supreme) product was used by the test subjects.
In a similar fashion as with the Swift study, a continued color improvement was noticed over the entire 6-week period. And this study concluded that there was no evidence of increased adverse events (side effects) with extended treatment through 6 weeks.
Do these studies suggest that using additional boxes of whitening strips on your own is OK?
No, we won’t concede that point. Instead, we feel that they confirm that having your dentist involved makes the only appropriate plan when extended treatments are considered.
a) Side effects.
We will agree that the two studies above do suggest that side effects aren’t usually a problem with extended (up to 6 weeks) use of both the high and low peroxide concentration WhiteStrips® products evaluated.
But that wasn’t a foregone conclusion of either study. Instead, the possibility of experiencing side effects was anticipated, and the subjects were monitored (“supervised”) in case they did arise and needed to be managed.
That’s a different scenario than takes place with unsupervised at-home use (where there’s no support system already in place if assistance is needed).
b) Teeth whitening potential.
The Swift paper specifically discusses the issue of the “whitening plateau” (a point where no further whitening takes place) that is expected to occur with teeth bleaching treatments.
The only possible justification for using additional kits of whitening strips is if the plateau has not yet been reached. But without a dentist’s supervision, we don’t think that most people can determine when this endpoint has occurred. And the indiscriminate use of teeth whiteners is never appropriate.
Using a shade guide to document the color of teeth.
Dental shade guides.
A person, on their own, could emulate this step. (We do see tooth shade guides available online, ranging from high-end professional ones to inexpensive paper ones, and even free printable ones). But short of having this type of objective before-and-after comparison, feel that essentially no at-home users can determine accurately when their whitening plateau has been reached.
Just our advice.
In any case where an objective measurement using some type of shade guide isn’t taken, and especially when the use of several additional whitening strips kits is involved, one would have to be concerned that some level of whitener abuse may be taking place.
As stated above, the indiscriminate use of whitening products is never appropriate. And it would be our feeling that anyone who has concluded differently must either know far more or far less about this subject than we do.
B) Using extra whitening strips for touch-up treatments. – How often? How many?
What do you need to do to maintain your whitening strips’ results?
Right about the time a person uses the last few of their whitening strips, two questions will typically come to mind. They are: 1) How long will their whitening results last? and 2) How often will touch-up treatment be needed?
These two subjects are the focus of the remainder of this page. And based on findings taken from research studies, we explain what level of whitening relapse can be expected. And how well the stability of the results achieved using whitening strips compares to other teeth bleaching methods.
Following that discussion, we then explain How to use whitening strips when performing your touch-up work.
How long will the whitening results you’ve achieved using WhiteStrips® last?
It’s normal and expected that the lightening effect created by all types of teeth bleaching methods, including strips, will fade over time. And therefore touch-up work will be needed from time to time to maintain your original results.
A number of studies have evaluated the level of this effect following the use of whitening strips specifically. And how the amount of relapse that does take place compares to other whitening methods. It’s generally been found that the stability of whitening results achieved using strips compares favorably.
Before and after.
Touch-up treatment is usually needed to maintain whitening results.
Study findings –
This investigation evaluated the color relapse that took place following different bleaching methods, including whitening strips, tray-based whitening, and professional/in-office treatments.
- At the completion of their respective whitening processes, test samples were evaluated for loss of “lightness” and return of “yellowness” at intervals out to 12 months.
- It was determined that all samples, regardless of the whitening process used, lost most of their achieved “lightness” over the following 12 months. In comparison, the “yellowness” of the samples was not found to relapse fully.
Study implications about touch-up work following the use of whitening strips.
Most importantly for this page’s discussion, the authors reported that “Generally, no differences between the bleaching agents could be observed.”
That means that the level of color stability associated with whitening strips use is on par with other bleaching methods. And as such, touch-up treatments will be required no more frequently.
Study title: Clinical trial of long-term color stability of hydrogen peroxide strips and sodium percarbonate film.
A part of this study’s design included comparing the “color retention” of treatments performed by test subjects using both whitening strips and a paint-on whitener.
- It concluded that “both peroxide-containing systems exhibited appreciable color retention throughout the 18-month post-treatment period.”
That means that relapse was observed. But even at 1.5 years out, much of the original whitening effect was still present.
Study implications about touch-up work following the use of whitening strips.
This suggests that whatever touch-up treatments are ultimately performed, it can be expected that the level of effect they’ll need to produce will never be as substantial as initially. (At least if performed within the first 1.5 years.)
This then implies that touch-up work can either be shorter in duration, or accomplished using a less potent whitener (strip), or both. (We discuss these issues below.)
Study title: Randomized clinical trial of the efficacy, tolerability, and long-term color stability of two bleaching techniques: 18-month follow-up.
Auschill evaluated the long-term color stability of two tooth whitening methods (whitening strips and tray-based bleaching) and determined that “at the 18-month recall, tooth shade remained significantly lighter than at baseline.” (Baseline being the color of the teeth before beginning their whitening processes.)
Study implications about touch-up work following the use of whitening strips.
These findings support those conclusions discussed above.
What we feel these studies collectively establish.
Based on their findings, it seems reasonable to us to state that:
- When whitening strips are used, some level of whitening relapse will occur. (A normal event associated with all teeth bleaching methods.)
- But even at a point 1 to 1.5 years following the strips’ use, noticeable (“significant”, “appreciable”) levels of the original whitening effect tend to still remain.
- And the degree of relapse that takes place following white strips use is similar to that that takes place following the use of other methods. (Which seems logical since they are all based on the same chemistry.)
What do strip manufacturers say?
When scanning through the pages of the WhiteStrips® (USA) website (this is the original whitening strips brand), we noticed their statements about the kind of results that they feel are typical.
▲ Section references – Crestwhitesmile.com
After using whitening strips, how often will touch-up work be needed?
Generally speaking, research seems to suggest that performing touch-up treatments somewhere between once a month up to every six months is generally all that’s required to maintain a person’s results over the long term.
It’s important to note that the total level of color relapse that ultimately takes place, and how rapidly it occurs, is affected by a number of variables. So, in regard to exactly what you experience, “your mileage may vary.”
A factor you control.
It’s generally considered that the degree and speed of relapse that takes place are influenced by your level of exposure to what’s termed “chromogenic agents.” These are dark-colored consumables, like coffee, tea, dark colas, red wine, and/or tobacco products.
If you’ll minimize your exposure (frequency and/or duration) to these kinds of items, the results you’ve achieved using your whitening strips should last longer and therefore make your need for touch-up treatments less frequent.
The nature of the relapse.
What touch-up frequency is needed after whitening strips use?
The last bit of information we’ve mentioned probably holds the key in determining how often you’ll need to re-whiten to maintain a consistent appearance.
It states that the greatest degree of relapse will tend to occur within the first 30 days immediately following the use of your whitening strips, and from there on remain more stable.
So if at a point 1 month out you’re still satisfied with your smile’s appearance (and therefore no treatment is indicated), a touch-up frequency of only every 3 to 6 months will probably be satisfactory (because this period equates with the plateauing of the rate of color decline).
What retreatment intervals are mentioned in published research?
It’s common to find touch-up intervals of every 30 days to 6 months discussed in studies. With a mention in some that some people still consider their original results acceptable even 1 to 1.5 years out.
We’re assuming that this latter group is composed of people who are somewhat less demanding about their smile’s appearance. But absolutely, if you don’t notice a need to perform additional teeth bleaching (at any point in time, no matter how extended), there’s absolutely no reason to do so. This is just a cosmetic issue and nothing more.
We think the wide range of this time frame (every 1 to 6 months) is simply an indication of how widely the level of relapse that occurs varies among people. And how a person’s feelings about their own need for touch-up work varies widely too.
How about shorter touch-up intervals?
When conducting our background research for this page, what we can say is that we didn’t run across a single study that suggested, or even discussed, a touch-up interval of less than every 30 days.
Using a shade guide to document the color of teeth.
How to perform touch-up treatments using whitening strips.
The contents of one foil package of Crest Whitestrips®.
For long-term storage, keep your extra strips in a cool dark place (your refrigerator is ideal).
How many whitening strips are required for touch-up treatments?
The idea is that you only need to use that (small) number of strips that are necessary to restore your smile’s appearance.
- So in cases where the amount of relapse that’s taken place is just minor (like when touching up every month or two), just performing one or two strip applications should be adequate.
- If a more substantial amount of fading has occurred (like when touching up at 6 to 12-month intervals), the use of a few strips (a few days of treatment) may be necessary.
You should never feel that you have to use more strips than just the number needed to rejuvenate your smile’s look.
What kind of whitening strips are best for touch-up treatments?
Since you have previous experience with a specific type of strip (whitener concentration, brand), and you’re simply trying to bring your teeth back to the same level of whiteness that that product did originally, sticking with the same kind can make a good idea.
Having said that, and especially if you’ve previously used a relatively high-concentration peroxide strip that has caused side effects, switching to a lower-concentration one may provide a more comfortable way to accomplish what you need.
Whatever kind you choose, no special instructions apply for touch-up work, just stay within your product’s guidelines found in its instructions.
Crest’s WhiteStrips® Stain Shield product.
In the past, we’ve noticed that WhiteStrips® has offered a product in its lineup named “Stain Shield.” We’re currently under the impression that this item has been discontinued (we no longer see it mentioned on the WhiteStrips® website (USA)).
These strips, touted as a solution for “daily staining,” are coated with a relatively low-concentration peroxide whitener and have a recommended application time of just 5 minutes. The idea associated with this product is that its daily use counteracts the normal fading process and/or formation of new staining in real-time.
It’s our opinion that incessant touch-up whitening performed for unfounded/undocumented reasons helps to establish a consumer mindset that can lead to whitener abuse. Generally, we think that this product tends to encourage that type of habit. So if Stain Sheild has been discontinued, we are glad to see it go.
Page references sources:
Auschill TM, et al. Randomized clinical trial of the efficacy, tolerability, and long-term color stability of two bleaching techniques: 18-month follow-up.
Bizhang M, et al. Clinical trial of long-term color stability of hydrogen peroxide strips and sodium percarbonate film.
Carey CM. Tooth Whitening: What We Now Know.
CrestWhiteSmile.com – Frequently Asked Questions.
García-Godoy F, et al. Placebo-controlled, 6-week clinical trial on the safety and efficacy of a low-gel, 14% hydrogen-peroxide whitening strip.
Monteiro D, et al. Evaluation of the effect of different enamel surface treatments and waiting
times on the staining prevention after bleaching.
Swift E J, et al. Effects of duration of whitening strip treatment on tooth color: A randomized, placebo-controlled clinical trial.
Wiegand A, et al. 12-Month color stability of enamel, dentine, and enamel–dentine samples after bleaching.
All reference sources for topic Teeth Whitening Strips.