A joint study by Graphy and the University of Bonn found that Graphy’s 3D-printed shape memory aligners effectively corrected anterior tooth rotations without attachments.
Graphy Inc and the University of Bonn have reported results from a joint study showing that Graphy’s 3D-printed shape memory aligners can correct anterior tooth rotations without the use of attachments. The findings were published in Frontiers in Bioengineering and Biotechnology in November 2025.
Preclinical Model Quantifies Rotation Correction
The research team used an electro-typodont model developed to quantify the rotational correction of aligners. The study, titled “Preclinical Evaluation of 3D-Printed Orthodontic Aligners Using an Electro-Typodont Model,” tested Graphy’s aligners made from its TC-85 shape memory resin.
The study was led by Professor Tarek M. Elshazly at the University of Bonn. Dr Hoon Kim, principal researcher at Graphy, was a co-author. Additional researchers contributed from Seoul National University, King Saud University, Mohammed Bin Rashid University of Medicine and Health Sciences, and the University of California, Los Angeles.
240 Aligners Tested for Efficiency and Reproducibility
The experiment used a model with a wax matrix simulating periodontal tissue. Tooth #11 was rotated in four increments: 22°, 32°, 42°, and 52°. For each case, four sequential aligners were 3D printed in three thicknesses—0.50 mm, 0.75 mm, and 1.00 mm—using Graphy’s shape memory material. A total of 240 aligners were produced, and five repetitions were performed per condition.
After the fourth aligner, 80.0 to 93.1 percent of the planned rotation was recovered. Residual rotations ranged from 4 to 5 degrees. Higher initial rotation angles resulted in higher relative recovery rates. Thinner and thicker aligners produced faster early movement, while the 0.75 mm thickness provided steadier correction throughout the sequence.
No attachments were used during testing.
Direct-Printed Aligners Compared to Thermoformed PETG
According to the authors, the results support the use of directly printed shape memory aligners for complex movements without auxiliary features. The electro-typodont model, they said, offers a consistent and measurable way to evaluate aligner mechanics before clinical use.
They also noted that Graphy’s material avoided some of the limitations of thermoformed PETG aligners, including changes in thickness and reduced edge integrity.
Shape Memory Resin Activates at Body Temperature
Graphy’s aligners are produced using a urethane-acrylate oligomer that returns to its original shape at body temperature. The material maintains the original digital design while delivering controlled force over time.
Ongoing Research Collaboration
The project is part of a broader research collaboration between Graphy and the University of Bonn that began in late 2022. The group is continuing to study the mechanical and biomechanical properties of shape memory aligners. This publication is the latest in a series of planned research outputs.
Photo: ID 84720668 © Irochka | Dreamstime.com
