Controlled-Contour Titanium-Zirconia Hybrid Prosthesis for Posterior Implants in Thin-Gingiva Phenotypes: A Preliminary Retrospective Cohort Study

Background To evaluate a hybrid screw-cement retained prosthesis combining prefabricated titanium abutments with customized zirconia transmucosal crowns for posterior implants in thin-gingival phenotypes. Methods This retrospective study evaluated 25 patients with thin gingival biotypes consecutively treated between 2023.5 and 2025.5, with all patients received 30 bone-level implants. The repair process was initiated three months after the operation, customized zirconia crowns were fabricated and bonded extraorally to titanium abutments with ≤ 30° emergence profiles, meticulously polished, and screw-retained at 35 Ncm after complete cement removal. Following digital scanning (TRIOS 4) at impression-taking (T0), delivery (T1), and 6-months post-delivery (T2), STL files were analyzed in Geomagic Wrap 2021. Outcome assessments included mucosal margin changes (vertical/horizontal displacement), gingival index (GI), bleeding on probing (BOP), keratinized width (KTW) at T0-T1, mechanical complications and crestal bone stability via periapical radiographs. over 12 months. Results The protocol demonstrated excellent peri-implant stability: mucosal positive changes (vertical: 0.38 ± 0.12 mm, horizontal: 0.29 ± 0.09 mm, p > 0.05), radiographically-confirmed crestal bone maintenance (no detectable resorption), and significant KTW increase (1.2 ± 0.3 mm, p < 0.001, remaining significant after Bonferroni correction). Inflammation control was evidenced by stable GI scores (≤ 1) and 62% BOP reduction (p < 0.01). No abutment fractures, screw loosening and crown debonding were observed during 12 months. Conclusion This retrospective analysis found that the proposed hybrid prosthesis protocol was associated with favorable peri-implant tissue responses and no mechanical complications over 12 months. The technique shows potential as a viable option for thin-gingiva patients, warranting further investigation in larger, controlled studies. Clinical trial number: not applicable