The Dermajet is very suitable for tummy-tuck and other surgery or accident scars or stretch marks but if you have only one scar and you're not going to need other needle lengths somewhere else on the body, buying a 1.5 mm dermastamp with 35 needles will be much cheaper for you. The dermastamp will eventually get blunt and you have to replace it but even two dermastamps are much cheaper.
If the scar is rather thick, apply our 0.1% Tretinoin cream right after stamping to soften the hardened collagen of the scar. On top of Tretinoin cream, apply our Infadolan ointment. Do not stamp the scar sooner than six weeks after the scar was formed.
If the scar is raised, perform the pressure massage described here:
https://http://forums.owndoc.com/dermarolling-microneedling/what-to-do-about-hypertrophic-scars/msg4877/#msg4877Concerning hyperpigmentation, the Dermajet can be used (you should set up the needle size for 0.5 mm) but if the pigmentation is all over your face, it will be much quicker to roll it with a regular 0.5 mm dermaroller (up to three times a week) and then apply hydroquinone cream:
https://http://forums.owndoc.com/dermarolling-microneedling/african-american-pigmentation-1161/You can also try the Tretinoin cream (it helps very much with post acne spots) but the 0.1% that you need for your surgery scar is too strong for the face so mix it with another cream (any cream you like) to dilute the percentage (or buy our 0.5% Tretinoin cream and use it both for your face and for your scar).
The most serious/dark post acne spots should be stamped with a 1.5 mm dermastamp every three weeks in addition to your 0.5 mm dermarolling sessions. Again, you can use a Dermajet but a 1.5 dermastamp with 35 needles is perfectly OK and suitable as well. The dermajet becomes cheaper than dermastamps & rollers when comitting to a multi-year needling regimen or when planning to buy many different rollers/stamps.