There is no consensus on how often you can use teeth whitening strips but it is not recommended to whiten your teeth every single day. Spacing out the treatments and taking breaks in between is advised because you don't want sensitive teeth all year long.
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What whitening strip manufacturers say about frequency of use
Surprisingly most of the brands are fairly vague in their directions in regards to how often you should be using their products. Most of them simply give you the directions to finish the first round of treatment but then don't say anything about touch ups.
Moon oral care: Place one strip on front of teeth (one for top and one for bottom). Let dissolve (takes about 15 minutes). For best results, avoid eating or drinking for 30 minutes after use and use two times a day for 14 days.
Lumineux: Recommended Routine - Use strips 7 days in a row, then 1-2 times a week thereafter to maintain your white smile!
Snow: Use one to two times per day for 14 days. For best results use two times a day.
Crest: USE ONCE A DAY FOR 30 MINUTES. Treatment length when used per directions lasts 16 days. For full results use entire kit. Use up to two kits per year.
Most of them don't say anything about usage after completing treatment except for Crest and Lumineux.
Crest says you can use a total of two kits per year. The first kit you use it all consecutively so we're going to assume the second kit is for touch ups. Since there are 16 treatments in a box, its safe to say you can use one as a touch up every 3-4 weeks.
Lumineux is actually fairly generous with their recommendation in that you can use their products 1-2x per week even after completing treatment.
However you should be aware that the Lumineux whitening strips do NOT contain hydrogen peroxide. It is a peroxide-free whitening product so that is most likely the reason why they are so "generous" with their recommendation. That product is coconut oil based.
Can I use whitening strips everyday?
Objectively based upon what the instructions for all of various brands of whitening strips have to say, none of them mention anything about everyday use. That is right, there isn't a single one which says it is appropriate to use their product 365 days a year.
I mean you would think that they would want you to continuously use their products and keep buying them. Perhaps there is a reason why they don't have it listed? If you want our opinion on it, it is simply because it is a potential liability issue. There aren't any long term studies in regards to the effects of hydrogen peroxide on the teeth.
Since no one knows what may happen to your teeth or your health from long term whitening strip use, the manufacturers are hesitant to make an explicit recommendation.
For the most part that is true but we did manage to find ONE study about "long term whitening use". It was basically one test subject who whitened their teeth everyday with a 10% carbamide peroxide solution for 6 months straight.
The patient had severe tetracycline staining on their teeth so they were very motivated to get them whiter. At the end of the six months, the patient did not experience any adverse effects nor did they lose any of their teeth. Suffice to say they were the same oral health wise as before they started the treatment.
With that being said... that is a single study based upon one person so it is not clinical evidence that using whitening strips everyday is appropriate. You need a much larger sample size than that in order to make a claim that you can whiten your teeth for 6 months straight. Therefore we cannot recommend that you use whitening strips everyday based on that one study.
What happens if you use whitening strips too often?
No one really knows what the consequences of using whitening strips are and that is why there are no recommendations to do so. There are simply no long term studies on the effects of exposing teeth to hydrogen peroxide although teeth sensitivity is a common adverse effect.
However there are studies about the safety and toxicity for hydrogen peroxide at least short term. According to a study in the Journal of Dentistry, peroxide can potentially be cytotoxic to the tooth pulp in high concentrations.
They tested various concentrations of peroxide with different treatment times:
35% - 3 x 15 mins
35% - 1 x 15 mins
35% - 1 x 5 mins
17.5% - 3 x 15 mins
17.5% - 1 x 15 mins
17.5% - 1 x 5 mins
What they found was that all of them recovered from the toxic insults except the high concentration for long duration of time. However when they reduced the exposure time for the high concentration, the toxicity disappeared.
Their conclusion was that highly concentrated products should be used for a shorter duration. Lower concentration products can be used for a longer period of time.
If we're to extrapolate the findings in that study and apply it to whitening strips, it's probably safer to use the strips more frequently than in-office whitening sessions. Meaning you can use the whitening strips more often in a single year than getting it professionally whitened. That is because the strips are a lot less concentrated than what you get at the dentist.
What about all natural and peroxide free strips?
We may not know the effects of what peroxide has on our teeth long term but all natural products like Lumineux strips we do. It is coconut oil based and you can certainly cook with coconut oil everyday so it's probably safe to use everyday. They explicitly say to use it once to twice per week but it's just coconut oil. You can certainly use it more than that can't you?
Takeaway
How often you should use whitening strips is more of an art rather than a science because there isn't an exact protocol for it. We know for a fact that the whitening doesn't last forever because teeth do restain over time so you are suppose to re-whiten them. However the various brands don't really give you any specific interval that you're suppose to do it.
They sort of just leave it to your own judgement because there aren't any long term studies on the effects of hydrogen peroxide on your teeth. We suppose it is just "use at your own risk". Our dentists in Long Island City say that you shouldn't do it everyday and should spread out the treatment. You should discuss further in depth with your dentist.
