Effect of phytosphingosine on staining resistance and microhardness of tooth enamel - Amorim, Ayodêle Alves; Arruda, Carolina Noronha Ferraz de; Vivanco, Rocio Geng; Bikker, Floris; Souza, Fernanda de Carvalho Panzeri Pires de (Journal of Esthetic and Restorative Dentistry, 2021)