Needling healthy tissue?

[Kimber]

I've read a lot about specialized devices for needling scars and stretch marks. What is the reason for avoiding needling the surrounding tissue? What is the problem with using a regular roller over stretch marks?

I know you need to needle scar very densely, is that density bad for unscarred skin? Thanks.

[SarahVaughter]

Scar tissue (stretch marks are scars too) contains thick and dense collagen bundles. If you manage to crush the bundles, it will smoothe the texture and often even improve the color of the scar. A dermastamp or single needles are more effective tools for that.  Also, scar tissue is harder to penetrate for the needles than scar-free tissue and to "crush" it, it needs dense, "aggressive"  dermaneedling. There is no problem to hit scar-less skin but you should concentrate on the scar tissue because that is your target.  Scar tissue has also very low metabolic activity and dermaneedling often improves it a little.

There is neither any problem with using a regular dermaroller over stretch marks; on the contrary, it is very useful but the most effective approach for scars is to combine a dermaroller (roll over the entire area) with a more targeted tool (a dermstamp or the single needle) that concentrates on individual scars.