Management of Severely Reduced Interimplant Distance Using a Novel Eccentric Abutment: A 6-Year Case Report Featuring Digital Quantification of Implant Spacing.

Background: A minimum interimplant distance (IID) of 3 mm has been recommended to preserve the interproximal bone crest and soft tissue papilla. In immediate full-arch rehabilitations requiring tilted posterior implants, anatomical constraints may not allow such spacing. When implants are placed in close proximity, conventional angulated multiunit abutments (MUAs) can lead to prosthetic interference and compromised mechanical resistance. This case report describes the management of two tilted implants with an IID <1 mm using a novel eccentric MUA. Implant spacing was precisely quantified using a superimposition-based digital workflow. Case Presentation: A 72-year-old woman underwent extraction and immediate placement of six implants in the maxilla for full-arch rehabilitation. Two posterior maxillary implants were positioned less than 1 mm apart. This prevented the use of conventional angulated MUAs. An eccentric MUA providing a 3.6 mm horizontal offset enabled restoration of adequate prosthetic spacing. A definitive prosthesis with a titanium laser-welded framework and composite veneering was fabricated and delivered 24 h after surgery. At the 6-year follow-up, no biological or major mechanical complications were observed. In the narrow interimplant area, bone extended above both implant necks and the papilla persisted. After unscrewing the prosthesis, digital intraoral scanning with scan bodies and STL superimposition allowed digital measurements of the IID. Conclusions: This 6-year case report documents the use of a noncustomized eccentric MUA with a 3.6 mm offset as a practical solution for managing an IID <1 mm. This was achieved without compromising prosthetic function or papilla formation. The crestal bone between the close implants appeared to remain stable over the follow-up period. It is speculated that it may be related to the platform-switching design and stability of the internal conical connection. Further clinical studies are warranted to assess the biomechanical reliability of eccentric abutments and the long-term behavior of interimplant crestal bone when spacing is <1 mm.