Digital Technology of Making Impressions for Multiple Implant-Supported Fixed Restorations

Background: Digital impression technology is widely used in conventional dental fixed restorations and single-unit tooth implant supported fixed restorations, but faces challenges in accurate impressions for multiple implants. The conventional method currently used in clinical practice still requires a large amount of manual operation, long chairside time, and the quality of impression is difficult to guarantee. To overcome these limitations, this study proposed a novel personalized alternative method of impression making for multiple implant-supported fixed restorations based on digital technology and additive manufacturing. Methods: An intraoral scanner was used to obtain 3D data of the impression copings and the surrounding oral soft tissue. A hierarchical structuring was designed using computer-aided design (CAD) software, comprising a novel splinting framework and a corresponding patient-specific custom impression tray. The entire system was fabricated via additive manufacturing. The splinting framework was rigidly connected to the copings using resin, and the tray was guided into position by the splinting framework. The workflow was assessed via an in vitro impression simulation using a four-implant mandibular model and a clinical application in an edentulous patient with three implants. Results: The 3D-printed splinting framework achieved a passive fit in both in vitro and clinical applications. The gap between the splinting framework and copings was effectively filled with resin to establish a rigid connection. The annular step structure accurately guided the custom impression tray to the predetermined vertical position, ensuring uniform impression material thickness. In both the in vitro and the clinical case, the custom tray, splinting framework, and impression copings were removed as a single stable unit without separation or distortion. Conclusions: The proposed CAD-designed, 3D-printed splinting framework combined with a patient-specific custom impression tray demonstrated technical feasibility for multiple implant-supported fixed restorations. It may potentially reduce the face-to-face treatment time and facilitate fast and efficient chairside impression making.