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Updated: Jul 13, 2025
Author Spotlight: 3D Movement Assessment of Maxillary Posterior Teeth in Clear Aligner Treatment
Published on: February 23, 2024
A new way of analyzing tooth movement using universal coordinate system geometry single point superposition in a 3D
Rodrigo Xavier Silveira de Souza1, Gustavo Almeida Silveira de Souza2, João Pacheco Colares1
1Federal University of Minas Gerais, Faculty of Dentistry, Department of Restorative Dentistry (Belo Horizonte/MG, Brazil).
Introduction:
Superposing 3D models is an imminent need. However, current methods rely on marking multiple points on the maxilla and mandible, which could increase point marking and overlapping errors.
Objective:
This study aimed at developing a method for superimposing 3D models of the maxillary and mandibular arches with Autodesk Inventor® engineering software, using a single universal coordinate system (UCS) point superposition.
Methods:
A total of 104 STL (stereolithography) models of the maxillary and mandibular arches exported from My iTero® platform were retrospectively selected, in which T0 and T1 were the initial and refinement periods, respectively (n=26 per group). The X, Y, and Z coordinates associated with a single point in each arch were inserted into the models with SlicerCMF® software for model orientation. The arch models with UCS registration were transferred to Autodesk Inventor® for superimposition and to measure tooth movements performed during Invisalign® treatment. Arch expansion, intrusion and rotation were analyzed by two examiners. The statistics were performed using intraclass correlation coefficients (ICC), Dahlberg's formula, and t-test (p<0.05).
Results:
A reliable method of superimposing 3D digital models using a single UCS point in the maxilla and mandible was developed. ICC showed excellent intra- and inter-examiner correlation (ICC>0.90). A systematic error was not found concerning linear and angular measurements (<1mm and <1.5°, respectively). Digital dental movements could be analyzed, including arch expansion, dental intrusion, and tooth rotation.
Conclusions:
The developed method was proven reliable and reproducible for superimposing 3D models of the maxillary and mandibular arches by using UCS system.
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