Longitudinal, randomized, and parallel clinical trial comparing a violet light-emitting diodes system and in- office dental bleaching: 6-month follow-up - Sobral, Marina Ferreira Pires; Cassoni, Alessandra; Tenis, Carlos Alberto; Steagall, Washington; Brugnera Junior, Aldo; Bagnato, Vanderlei Salvador; Botta, Sergio Brossi (Photobiomodulation, Photomedicine, and Laser Surgery, 2021)