Treatment time of class II malocclusion, with and without mandibular crowding, treated with four premolar extractions: a retrospective study - Janson, Guilherme; Silva, Lucas Nunes Bastos Curty; Valerio, Marcelo Vinicius; Laranjeira, Vinicius; Niederberger, Ana; Garib, Daniela (Turkish Journal of Orthodontics, 2021)