The research indicates that it is. That is, any long-term study that has tracked people after their treatments has seen improvement that lasts beyond the last roll (cite).
By that, they mean that if you dermaroll a pitted acne scar for a course of treatment and that scar goes away, it’s gone for good. (A majority of the research on microneedling is on acne scars because that was the first application it was used for.)
With that said, I sometimes see questions from people who did a course of dermarolling or microneedling (either DIY or in an office) who saw their scars disappear but were then crestfallen to find that, if their acne comes back, they get new scars from the new acne. (This unfortunately seems to happen often to people who come off Accutane.) So, microneedling will cure a scar, but it won’t prevent that skin from scarring again if there’s another injury. You can still dermaroll the new scar to make it go away.
The same is true of dermarolling for fine lines, stretch marks and skin laxity. Done faithfully, dermarolling will improve and rejuvenate your skin, and a maintenance routine will encourage continued skin turnover, slowing the aging process. But it won’t keep you 22 forever! Dermarolling lines is permanent in that if you stop dermarolling, the younger-looking results you’ve attained are your new natural skin condition, as opposed to a serum or moisturizer that only works for as long as you’re using it every night. Similarly, the dermaroller will reduce or eliminate your stretch marks, but it won’t prevent you from ever getting them again in that spot–again, if you did, you’d be able to roll the new ones too.
Similarly, conditions with a hormonal basis like melasma (hyperpigmentation or sunspots) will see benefits from dermarolling, but those benefits can be undermined by a hormonal swing. This happened to me with pregnancy melasma–I had just about treated all of the discoloration left over from my first pregnancy, but the second I hit my second trimester in my second pregnancy, there it was again in the same spots! The dermaroller had removed the first set of spots, but new spots appeared from the new crush of hormones.
As far as my own anecdotal experience–yes, the dermaroller effects are permanent. My skin looks AMAZING for a day or two after I dermaroll due to the mild swelling, which is just enough to make my fine lines and pores seem to disappear. Once that swelling goes down, my face looks more or less the way it did before, because you don’t see the full effects of a roll for six weeks! But the cumulative effects of my rolls for the past three years are indisputably permanent.