do teeth whitening gels really work?

My teeth are not that white and would like to use a tooth whitening gel to make them better. if you have alredi used any tooth whitening gels can you please state which ones and how they worked for you? i had the following couple of gels in mind. would they work too? because im thinking of purchasing them today. http://www.boots.com/webapp/wcs/stores/s… http://www.boots.com/webapp/wcs/stores/s…
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I use crest white strips and I think if you follow the directions on them and use them properly they work well, and ive also used 3 different kinds of gel whitening kits with a blue light it comes with to whiten it. I think they work pretty well too, but it is important to keep up with it and use things like whitening mouthwash. I think the gel stuff you chose will probably work cause all of the whitening things ive used have worked pretty well. Good Luck!
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