Yesterday I was practising the solo from Iron Maiden's Wasted Years with the help of a video.

The solo isnt too difficult for me, but I have lots of problems with the bends, I mean, I can bend the string to the desired pitch, but I have TONS of problems keeping the other strings muted if I bend lets say the high E string at fret 20 1 step, I will move/touch the B and G strings aswell, Ive been trying different things to avoid them from doing noise, but I cant get a definitive technique

btw the guy in the video (Danny Gill) does it flawlessly!!! making me feel like a noob!!! bastard!

im not sure how he does it, bending with middle finger while muting the strings with the pointer? might work, but I have problems if I have to do a pulloff rightaway etc ...

any suggestion on this?

he makes you feel like a noob? i swear he was taught by joe satriani or someone at one point...
technique comes with practice......................TECHNIQUE!!!!!!!!!!!!!!!!!!!!!!!!!
If you're having problems muting the other strings then what you gotta do is PRACTICE Palm Muting Techniques! The Picking hand is just as important!. And remember it's best to bend using your 3rd finger with your 2nd finger for support and quick recovery.
Try some blues they got alot of stuff like that and remember start off slow because Danny Gill didnt learn overnight.
I have a little bit of advice, I learned something from a youtube vid a while back which helps to keep other strings muted, you use your index finger to mute 3 or 4 strings in a row, while going ahead with your bend with ring finger or 2nd finger. Good vid to see it being done is in zakk wyldes "farewell ballad", just watch how he mutes the strings via index finger, don't bend like this all the time of course but if you are having trouble then try it out.
Yep, I use my index to mute the other strings, and bend with the rest of my fingers. Another factor is the action on your guitar. If the action is low, the string being bent is pushed into the other strings, and not too much work is needed by the index to keep them quiet. If the action is high, the bent string wants to go under the others, and all hell breaks loose, so a lot more attention has to be paid to muting.
Like everyone says mute the strings, but it might be your vibrato you need to work on.

And your feel for the guitar, start practicing the bends on a clean tone and work from there.