Accuracy of full-arch implant scan with Nexus IOS® scan gauges versus different conventional scan bodies: An in vitro comparative study

OBJECTIVE: To evaluate the accuracy of full-arch (FA) implant scan with a novel system (Nexus IOS®, Osteon Medical) using scan gauges (SGs), and to compare it with that of different conventional scan body (SB) systems that are currently available. METHODS: A plaster model with 4 multi-unit-abutment analogs was prepared and inter-implant distances between its analogs were measured using a coordinate measuring machine (CMM), to obtain reference distances. An expert operator used an intraoral scanner (IOS) to capture scans with five different systems (Nexus IOS®, DESS®, Medentika®, IPD® and Elos®, n = 10 scans per group). These measurements were compared with the reference CMM-generated model to calculate inter-implant distance trueness. The study design addressed three questions: 1) Are there overall differences among the systems? 2) Are there overall differences among segments/points? and 3) For a given segment did systems perform differently? A statistical analysis was performed. RESULTS: Among the systems, Nexus IOS® system exhibited the highest trueness, followed by DESS®. Medentika® and IPD® showed slightly higher deviations and variability, indicating moderate performance. Elos® had the least trueness among the systems tested, with the highest median deviation and the widest overall spread, suggesting greater inconsistency in dimensional accuracy. CONCLUSIONS: Within the limitations of this in vitro study, the Nexus IOS® SGs demonstrated the highest dimensional accuracy, showing superior trueness and precision in FA implant scanning compared with conventional SBs. STATEMENT OF CLINICAL RELEVANCE: These findings support the potential of calibrated SGs to improve digital FA implant accuracy and consistency, aligning with emerging literature on calibrated and framework-based scanning approaches.