Clinical acceptability and repeatability of three-dimensional maxillary positioning following orthognathic surgical wafer placement: An in vitro study

Abstract

Objectives: To quantify the three-dimensional (3D) deviation between planned and achieved maxillary positions after transfer using a surgical wafer under in vitro conditions, and assess clinical acceptability and repeatability for each workflow. Methods: A bracketed typodont mounted on a mannequin was used to define three groups-Conventional (alginate impressions/plaster casts/laboratory scanning), Trios (Trios 3 intraoral scanner (IOS)), and Prime (Primescan IOS)-each with 10 technical replicates. For each replicate, virtual surgical planning was performed, a wafer was designed and 3D-printed, and the maxilla was positioned; 3D deviation was quantified as: (1) point-based 3D positional deviation (three landmarks) and (2) matrix-based 3D translational and rotational deviations. Clinical acceptability was defined as the proportion of the 10 replicates per group with 3D deviation within predefined clinical tolerance limits (0.5 mm for positional/translational; 1.0 degrees for rotational). Repeatability was summarized by the repeatability standard deviation (sr) as specified in ISO 5725. Results: The Trios and Prime groups achieved 100% clinical acceptability across all 3D deviations. In the Conventional group, acceptability was 90% for the anterior landmark's positional and translational deviation, with all others achieving 100%. The sr was 0.13-0.20 mm (positional), 0.23 mm (translational), and 0.22 degrees (rotational) for the Conventional group; 0.04-0.13 mm, 0.06 mm, and 0.24 degrees for the Trios group; 0.04-0.10 mm, 0.11 mm, and 0.17 degrees for the Prime group. Conclusion: Under in vitro conditions, the demonstrated clinical acceptability and repeatability provide preliminary evidence supporting the clinical feasibility of a fully digital IOS-based workflow for wafer-mediated maxillary positioning. Clinical significance: An IOS-based workflow can be considered clinically feasible for wafer-mediated maxillary positioning without compromising accuracy, as evaluated in terms of clinical acceptability and repeatability, while potentially eliminating impression-taking and cast fabrication steps.