Opalescence 35% Gel Syringes Teeth Whitening - Refill Kit (6 Pack / 12 Syringes), Made by Ultradent, Carbamide Peroxide in Mint Flavor. Tooth Whitening 5197-12

UPDATE July 2015I have now used this product for about 8 years exclusively. Throughout that time I never returned to the dramatically yellow teeth I had. Last year I replaced the top 2 front teeth that were veneers with new crowns that used new technology. I decided to get the crowns even whiter, down to a BL4. So that is whiter than natural teeth, but not by much. So the challenge was to bleach for about 3-4 weeks to get the teeth next to them down to a BL4 from about a B2.I still use the custom trays the dentist did 8 years ago, but at this point I NEVER burn my gums. After practice, you will never burn your gums either. The trick is good custom trays combined with experience. You still have to deal with a little sensitivity, but it is well worth it, and is temporary for me.I successfully whitened most of the teeth between a BL4 and a B1. With the new crowns in, the teeth look great for someone in their 50's. The teeth look totally natural, too.Last week I did 4 days of touch up and they look even whiter in a short period.Good luck!--- Original 2007 ReviewWith products as this, it is best to precursor the review with some instruction and expectation setting:Instructions:--This product is meant to be used as a refill to custom trays fitted by your dentist. Otherwise, you will have issues with uneven application and gum burning.--Application must follow instructions that are provided. Do not over apply or the gel will burn your gums and turn them white for a little while.Expectations:--At the end of the day, research suggests that the 35% whitens as much as the 15%. The difference is twofold: The 35% needs to onlt stay on for 30 minutes, but the 15% needs to stay on an hour. Second, the 35% will get your teeth whiter faster. E.g., if it takes 12 weeks for the 15% to get to the desired whitening, it may take 8 weeks for the 35%.--The 35% will make your teeth more sensitive than 15%. For me, it was worth the extra sensitivity to get faster results.--It takes time! Results do not occur overnight for most people. Expect 12-16 weeks, applying once a day at night for 30 minutes. If it occurs faster, use the remaining gel to periodically keep them white.--The gum line part of the tooth may still be yellowish. My guess is it is hard to get right to the gum line without burning. So the application will still be a little uneven.My review:I had noticeable results after 4 weeks, from 2-4 shades. One tooth was 4 shades, most were 3, and the rest were 1 to 2. I am under Dentist care for the entire process.For the 4 week period, the Dentist was highly pleased with the progress. I was pleased as well. After 6 weeks, though, the progress seemed slower, and the lower teeth are still too yellow.As well, one issue remains: one upper front tooth would not whiten well. It had undergone trauma when I was young. So, the 2 upper front teeth will need veneers. Right now it is a race to whiten as much as possible to get the whitest shade of veneers possible.My method:-- I used 12) 15% gel for 6 weeks that the dentist provided-- I used (8)35% gel for 4 weeks that I bought from Amazon-- I applied twice a day for at least half the time-- I used between 1/3 to 1/2 of the syringe per applicationIn all, you have to be patient and not expect quick results. Some teeth will whiten faster and others may not whiten much at all. From what I researched and the Dentist's input, results widely vary. However, you should certainly see viable results and the effort is not hard. 30 minutes after bushing and flossing is pretty easy.I disagree with the low ratings for this product. Just because someone does not use the product properly, does not reflect on the product quality. Results based on non-custom trays are invalid in my opinion and should not reflect on the rating.

Edit/Edit - It took me almost a month of almost nightly whitening to get to my desired shade, so in total of 6 syringes of 10% carbamide. I'm too lazy to share before/after photos. I'll stick with buying this product for all maintenance whitenings going forward. I'm going to finish off the last two tubes to see how close to optic piano-key white I can get with 8 syringes.Edit: After an initial 5 nights of whitening my teeth were pretty white, but part of this was due to the teeth being dehydrated (and thus more sensitive). When you take a break for 1-2 days the teeth yellow a bit as the teeth rehydrate. So I started on another regimen, and am now on the 5th night of the second round, with 0.33 in 1 tube out of a total of 4 syringes used over 14 calendar days. Now I want to keep going to see if I can make my teeth look like piano keys.These work very well in your clear retainers. No need to purchase a separate custom whitening tray just for this. Check out the YT videos on how much to actually apply to each tooth-- it's just a small bead needed to the front of each tooth. I don't express a whole line of gel across the arch, this would be too much product.Also be aware that this is a perishable product. When I received the package, it had a remaining shelf life of 6 months. After, the gel loses efficacy. It doesn't drop to zero after this date, but just something to note. Amazon comped me an additional 8 syringes at no charge when I asked about the short shelf life.Start with buying 2 packs / 4 tubes of 10% Opalescence carbamide. I bought 4 packs / 8 tubes and there's no way I can get through all this stuff. I used only 1.75 tubes doing upper and lower arches for 6 nights and got to a very nice white shade, and any more my teeth would start to look like piano keys. I would've had to start from a much darker yellow shade in order to actually use up 4 tubes and go through two whole weeks of nightly whitening. And perhaps my teeth are more sensitive than others-- Definitely glad I started with 10% carbamide and not anything higher. By the 4th or 5th night I was starting to notice increased sensitivity, despite me having brushed with Sensodyne multiple times a day, every day for over a month prior. I also had braces removed a week ago, and experienced zero sensitivity during that procedure, for reference.