The peri-implant mucosal barrier “seal” plays a significant role in maintaining peri-implant health, but its efficacy in the presence of inflammation is lower than that of natural teeth due, primarily, to the absence of collagen fiber insertion into the implant/abutment surface. To test the influence of cementum upon collagen fiber insertion/orientation after tooth removal, a customized root-cementum abutment was fabricated using a natural tooth root fragment. For that, an extracted root fragment, preserving both cementum and periodontal ligament, was cemented to the titanium abutment and used as a healing abutment of an immediate implant placed into the fresh extraction socket. Three months after implant placement, firm resistance to probing was noted clinically upon follow-up evaluation and histological and FE-SEM analyses confirmed perpendicular collagen fiber embedding into the root-cementum abutment surface. This proof-of-concept unveils the role of cementum on fiber insertion/orientation and sheds light on the relevance of enhancing the sealing of the peri-implant mucosal barrier to protect the underlying bone by utilizing a customized abutment that allows for the insertion of connective tissue fibers.