Hi,
Generally, after an effective acne scar treatment e.g. fractional CO2 laser treatment, new collagen builds up progressively over the next 2-6 months and tends to be long-lasting translating to sustained improved clinical results that lasts years.
The caveat to the above is that not all acne scar treatments are equally effective so the collagen build-up relative to different treatments and even different treatment parameters used may differ significantly.
