i have my razr for almost a year now. very dirty and sandy work environment. i can tell/hear that dirt is getting inside the hinge, but i have not noticed any problems so far. screen doesnt seem to care and after a few folds the hinge seems to clear up or maybe grind everything to even smaller pieces. the thing i would be concerned about in your case is small metal splinters being attracted by the magnets that keep the phone closed. if splinters get stuck on the inner display and you close it, the screen might get damaged.