Metrological Accuracy of Conventional versus Digital Maxillomandibular Relationship Records in Implant-Supported Full-Arch Rehabilitations: A Systematic Review

Introduction: Accurate maxillomandibular relationship records (MMRR), encompassing centric relation (CR) and vertical dimension of occlusion (VDO), are foundational to the success of implant-supported full-arch restorations. Conventional analog techniques, though globally established, involve multi-step clinical and laboratory phases prone to cumulative transfer errors and dimensional instability. While digital workflows utilizing intraoral scanners (IOS) and photogrammetry aim to streamline this step, their metrological performance on long edentulous spans remains scrutinized. This systematic review critically compared the trueness, precision, and clinical efficiency of conventional versus digital MMRR methods in completely edentulous patients.

Methods: An electronic search was performed in MEDLINE (via PubMed) and the Cochrane Library for peer-reviewed articles published between 2015 and 2025, following the PRISMA guidelines. The primary outcome was the metrological accuracy—defined by trueness and precision—of the interocclusal relationship records. Secondary outcomes evaluated clinical chair time, workflow optimization, and post-insertion prosthetic adjustments.

Results: A total of 29 studies were analyzed. Synthesized data revealed that digital MMRR methods provide a clinical accuracy fully comparable to conventional registration protocols. Recent in vivo evidence demonstrated that advanced IOS systems achieve significantly superior trueness (42.3±18.7 μm) in capturing the maxillomandibular position compared to conventional analog techniques (67.8±24.1 μm, p<0.01). Clinically, digital workflows reduced chair time by approximately 28% and condensed appointments through single-visit "scan-and-record" protocols. However, outcomes heavily depend on hardware selection; only high-end IOS models consistently minimized stitching errors across long edentulous spans. Auxiliary digital technologies, such as milled verification jigs or photogrammetry, significantly enhanced record reliability.

Conclusions: Digital MMRR techniques offer a highly predictable alternative for full-arch implant rehabilitations, demonstrating equal clinical precision and, under optimized protocols, superior trueness to conventional methods. Successful integration relies on utilizing validated scanning strategies and advanced hardware.