Study sponsored by Align Technology and based on adult Class I, nonextraction, mild to moderate crowding cases with SmartTrack material. David W. White, Katie C. Julien, Helder Jacob, Phillip M. Campbell and Peter H. Buschang, Discomfort associated with Invisalign and traditional brackets: A randomized, prospective trial. The Angle Orthodontist Nov 2017, Vol. 87, No. 6 pp. 801-808