I have purchased the 35%:This whitening gel was recommended by my dentist. Ive already got a custom fit night guard / mouth tray purchased from my dentist Recommended use by a dentist. Dentist suggested I got this refill gel for my bi-monthly teeth whitening maintenance.1 - I see that this brand also sell their own whitening kit (the one with the gel + the mouth tray) but since Ive already got the customized mouth tray made by my dentist, I didnt get the whitening kit, instead Ive just got this whitening refill gel. Using my customized whitening tray makes sure that the gel dont run or slide into my gum area and avoid sensitivity. With or without having your own customized mouth tray, I would suggest to use a cotton swab to apply the gel directly on your teeth, instead of put the gel on the mouth tray, apply using a cotton swab to apply on teeth can avoid spreading the gel onto your gum. My dentist suggests that when using this refill, remember not to let the gel to touch your gum, if it does, wipe gel off.2 There are 5 big tubes in the refill, it lasts for months for me since I am only using it for maintenance. You only need to use a small amount and apply the gel on your teeth, less is more , just make sure it covers your teeth front surface and dont apply heavily or the gel will spread to other areas in your mouth which you dont want that. When you are using the gel, you might need to use a small towel just in case, just like any other whitening procedure, you will have saliva obviously and saliva might make things messy, but you can always spit out the saliva during the treatment.3 - I am a tea lover and I drink at least 2 cups every day. I avoid drinking hot tea or any hot beverages immediately after my home whitening treatment because hot and cold drinks right after the treatment might create sensitivity for some people (just like any other whitening treatments especially the ones done in my dental office, as my dentist use even more concentrated gel in his office.) I can still drink tea and my teeth keeps white, I will swoosh my mouth after drinking tea, and I always brush my teeth after each meal, thats my personal habit and my dentist appreciates it =) I would recommend you to at list swoosh mouth after dark color food / beverages such as coffee or tea even after the treatment. I use maintenance too, every 1-2 months or so, for maintenance I just use 2-3 days, depends how white I want my teeth to be.4 The box says keep gel in a cool place, so I always put the remaining of my gel in the fridge (NOT the freezer, just the fridge) I think by doing this it can last longer and keep its effective ingredients working next time.5 If the gel ever touches your gum, use a cotton swab to wipe it off your gum, otherwise you might risk making your gum sensitive or have a burning feeling. Remember, this products gel is used and recommended by dentists for teeth whitening, so its very effective, it works very well in terms of whitening your teeth, but you also need to be cautious and listen to the product instructions, it says a) use cotton swab to apply directly on teeth and b) dont get gel to touch gum. 3) use de-sensitized toothpaste before and after treatmentIf the gel spread to your gum, remember, you will need to wipe the gel off from your gum using a cotton swab or a soft tissue. You might also need to use cotton swab or a soft tissue to wipe off the part on the top of your mouth tray which got spread with gel and is touching your gum. Give it a few days of break in between if you experienced any sensitivity and reduce the 30 minutes per session down to maybe 10 minutes.I have done teeth whitening procedures at my dentists office before, it was way more expensive whitening at his office. After 2 times, I told my dentists if theres a more affordable way, he is so nice and he recommended this Crystal Clear refill for home whitening, and he says that all effective teeth whitening ingredients could cause sensitivity or burning feeling, it depends on how you manage it. He asked me to use desensitized tooth paste such as Sensodyne starting a few days before the treatment. He says this refill gel has good concentration of the whitening ingredients and also has this ingredient called potassium nitrates which it soothes sensitivity. He told me that since I have done my night guard / customized tray now I can do the teeth whitening maintenance at home myself if I want to save some money, I am very grateful to him telling me that, and this is refill gel is indeed very useful and effective for me and great results. I now only go to my dentist for regular checkup on my teeth grinding problem and for teeth cleaning. I can now my own whitening at home which saves me lots of $$$6 Hope writing this review or my own experience could help you. Its effective on my teeth, only way more affordable than to go to my dentist, just remember, use cotton swab to apply and wipe off the excess gel on my gum if...

I'm very impressed with this particular brand of teeth whitening gel pens. They are really helping to whiten my teeth and I've not had any irritation on my gums or mouth. Will definitely buy more in the future.

These work really well. I bought them as refills for my whitening tray. I can get 4 treatments out of each tube.

Whitens well and no bad taste. Wish there was a smaller tip on end of pen so can put gel on each tooth on tray.

Love this whitener