Badran, Abdelrahman, et al. “One Year Clinical Evaluation of Milled BioHPP Polyetheretherketone (PEEK)-Based Versus Metal Ceramic Single Crowns (Randomized Controlled Clinical Trial)”. Brazilian Dental Science, vol. 24, no. 3, July 2021, doi:10.14295/bds.2021.v24i3.2518.