If i'm understanding you rightly you're using the index finger to mute the higher strings? You shouldn't need to. Here's an example:
Let's say you're making a bend on the 15th fret on the B string up to the 17th and back down again. Your ring and middle finger should support the bend while the index finger should rest over the G and D string but don't push down that's the hard bit, is having control not to feel the urge to push down on those strings otherwise you will get string noise. Or at least that was the tough bit for me i kept noticing it would naturally push down because the other fingers were. Hope that made sense
nonono i'm mean this now i'm play the David A-minor penta lesson and there on A-minor scale i'm do this
||----------------------------|------------------------------|----------------------|
B||---------------------5------|-----5------------------------|----------------------|
G||---------5--7--7b-------7b--|--L-----7pbr--5---7---5b------|-------5b-------------|
D||-----\7---------------------|----------------7---7---------|--7-------------------|
A||----------------------------|------------------------------|----------------------|
E||----------------------------|------------------------------|----------------------|
so when im bend the 7 fret then i'm play after that with index fret 5 on b string so there is not easi to mute with index the lower string becouse after the bending i'm play the higer string