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Updated: Jun 4, 2026
Force System with Vertical V-Bends: A 3D In Vitro Assessment of Elastic and Rigid Rectangular Archwires
Published on: July 24, 2018
Biomechanical force profiles and force decrease of direct printed versus thermoformed aligners with different
Bernhard Wiechens1, Philipp Meyer-Marcotty2, Emilia von Waldthausen2
1Department of Orthodontics, Universitätsmedizin Göttingen, Göttingen, Germany. bernhard.wiechens@med.uni-goettingen.de.
Background:
This in-vitro study aimed to evaluate and compare the biomechanical force profiles of thermoformed and direct-printed aligners with different gingival trimlines during facial and palatal translation of a maxillary central incisor.
Methods:
A 3D-printed model with a mounted central incisor was used to simulate 0.25 mm of bodily movement. Forces were recorded in three axes (Fx, Fy, Fz) using a multi-axis force sensor. Three aligner types (thermoformed with straight trimline: TFAS, and direct-printed with either straight: DPAS or garlanded trimline: DPAG) were tested (n = 10 each). Vertical, transverse, and sagittal force components and their decrease were analyzed. Forces were recorded over 60 min to characterize initial force delivery and early stress relaxation under standardized in vitro conditions.
Results:
Thermoformed aligners exhibited the highest sagittal forces during facial movement (Fx - 0.70 N), while DPAG demonstrated significantly lower forces (Fx - 0.25 N; p < .001). During palatal translation, DPAS reached peak forces of 0.57 N, whereas DPAG showed lower, more controlled forces (p < .001). Vertical forces (Fz) were significantly higher in TFAS (- 0.10 N), while DPA remained near zero or slightly extrusive (p < .001).
Conclusions:
In this in vitro model, DPA, particularly DPAG, showed lower sagittal force values and smaller vertical force components. In the first 60 min, DPA showed a pronounced early force decrease. Longer observation periods are required to describe force behavior beyond the initial seating phase.
