How many Fraxel 1550 treatments are equal to one ablative CO2 Laser?

Hi There
If you are getting good results with Fraxel this is good, carry on. 
Fraxel coagulates the scar tissue (cooks it and kills it, causing it to be pushed out a few days later), the CO2 vaporizes the scar tissue (it vanishes in a puff of smoke) causing the skin to tighten a bit more.  You cannot really compare them as they have different effects - it is a bit like asking how many apples equal an orange?
Good Luck
Dr Dinesh Maini
Zenith Cosmetic Clinic

Impossible to answer that question as it depends on the settings. Regardless, scar revision should not be approached with only 2 lasers, its finding the correct METHOD. Acne scar revision is a specialised field. For the best results, one should target the acne scar type with ideal treatments. The web reference below will take you to a resource. I embedded all the videos in one page to help.

For example deep ice pick scars, and narrow box car scars can be treated with TCA CROSS peels, mixed scars, rolling, and atrophic scars treated with fractional devices such as Fraxel, fractional lasers, PRP and INFINI radiofrequency. Atrophic scars (depressions) can be treated with either fat grafts, or with HA dermal fillers. Tethered and anchored scars are best treated with surgery.

The majority of patients will have a collection of different scar types, and hence a tailored treatment METHOD will be best. Careful examination, especially under angled lighting with scar mapping will give you an understanding of what are the best options for your scars.

All the best,

Dr Davin Lim. Acne scar dermatologist specialist. Brisbane, Australia.