Almost every case will cause some sort of scratching of the iPhones. This is NOT due to the cases themselves but caused by dirt, dust, lint and many other types of tiny particles which manage to get in between the case and the iPhone; whether they are on the case before installation or get in there while the case is on, it's bound to happen eventually.
I've had every type of case from incipios to BookBooks to otterboxes to apple bumpers to ElementCase's to mophies etc and they all caused scratching one way or another after being on for long periods of time. I even took the phones out and cleaned both the cases and the phones frequently to prevent this but it'll happen.
Of course you'll always hear some ppl say I've had cases on all my iphones since the first iphone and never one scratch EVER, and I've come to the conclusion that these ppl somehow either are extremely lucky or maybe their lifestyles are such that their phones only see the inside of their extremely clean pockets and their extremely clean workplace desks and extremely clean cars and they have never dropped it on the ground or slipped in between the cracks in their cars or mowed the lawn with it in their pockets and never been in a dusty environment and they have really clean dryers which accumulate 0% dust/lint/dirt.
I don't know what else to tell you besides the ONLY way to fool proof 100% prevent from all scratches is to do a full zagg then cover it with a case or front and back screen protectors of some kind and a lucky lab type side protection and cover it with a case. But even then, sometimes dirt will accumulate where the screen protectors end near the edges and cause scratches. Lol
Good luck!
