Clinical study on the association between keratinized mucosa and peri-implant health when external hexagon implants are installed in the posterior region of the maxilla and mandible: a cohort study - Carvalhaes, Juliana Mandello; Ponzoni, Daniela; Tonini, Karen Rawen; Carvalho, Paulo Sérgio Perri de (International Journal of Oral and Maxillofacial Surgery, 2024)