I finished about 2 years of protrusive mouth correction in 2014, and I am currently in my 5th year.
There have been no problems, and it was orthodontic treatment with 4 extractions, but my protrusive mouth was completely corrected (to a surprising degree).
Even at the time, the orthodontic cost was on the very expensive side, but I am satisfied because the results and aftercare were good, and the doctor was kind.