A Human Self-Locking Cone Morse Connection Retrieved After 30 Years: A Histological and Histomorphometric Case Report

The Cone Morse (CM) implant-abutment junction is designed to improve screw mechanics and minimize bacterial leakage through a process known as “cold fusion”. This research evaluated a clinically stable self-locking CM implant that was retrieved after 30 years of functional loading, focusing on the bone–implant interface. Histological evaluation was conducted to assess the extent of bone-to-implant contact (BIC), identify any tissue reactions, and determine the overall condition of the interface. The analysis revealed a high percentage of BIC in the endosseous portion (56.9%) and at the first contact point (77.4%). Notably, the bone in direct contact with the implant showed healthy integration, indicating no signs of adverse reactions or degradation despite the long duration of functionality. Additionally, osteocyte lacunae were found to be more numerous and larger in the coronal region compared to the apical region. These findings confirmed that the CM implant design sustains a high degree of BIC in humans, even after extended functional loading. The absence of epithelial migration, inflammatory infiltrate, and fibrous tissue at the interface suggests that this type of implant can offer long-term stability and integration.