Geometry Alteration of Orthodontic Microimplants Following In Vivo Loading: Microanalysis on 3D Scans—A Cross-Sectional Study

This study aimed to assess three-dimensional geometric alterations of orthodontic microimplants associated with clinical loading. Twenty orthodontic microimplants (AbsoAnchor SH 1312-08) were scanned with a blue-light 3D optical scanner at a resolution of 2 μm. After sterilization, the microimplants were inserted and immediately loaded in adult patients undergoing maxillary molar intrusion. Upon completion of treatment, the retrieved microimplants were rescanned and digitally superimposed on baseline scans using a best-fit alignment algorithm to quantify surface deviations relative to the original geometry. All analysed microimplants demonstrated statistically significant geometric alterations (p < 0.001). Analysis of 88,565 measurement points revealed mean deviations consistently indicating inward deformation or material loss, with 95% confidence intervals remaining entirely negative (−0.01032 to −0.00998). Maximum local deviations approached 100 μm, primarily affecting thread depth and axial elongation, while one microimplant exhibited pronounced bending deformation with an arched configuration. These findings indicate that orthodontic microimplants undergo statistically significant three-dimensional microgeometric changes following in vivo loading; however, no clinically relevant adverse outcomes were observed.