Related Experiment Video

Updated: Apr 28, 2026

Author Spotlight: 3D Movement Assessment of Maxillary Posterior Teeth in Clear Aligner Treatment

Author Spotlight: 3D Movement Assessment of Maxillary Posterior Teeth in Clear Aligner Treatment

Published on: February 23, 2024

Forces and moments generated by removable thermoplastic aligners: incisor torque, premolar derotation, and molar

Mareike Simon¹, Ludger Keilig², Jörg Schwarze³

¹Orthodontist, Department of Orthodontics, University Hospital of Freiburg, Freiburg, Germany; doctoral candidate, Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.

American Journal of Orthodontics and Dentofacial Orthopedics : Official Publication of the American Association of Orthodontists, Its Constituent Societies, and the American Board of Orthodontics

|June 2, 2014

Abstract

Introduction:

The exact force systems as well as their progressions generated by removable thermoplastic appliances have not been investigated. Thus, the purposes of this experimental study were to quantify the forces and moments delivered by a single aligner and a series of aligners (Invisalign; Align Technology, Santa Clara, Calif) and to investigate the influence of attachments and power ridges on the force transfer.

Methods:

We studied 970 aligners of the Invisalign system (60 series of aligners). The aligners came from 30 consecutive patients, of which 3 tooth movements (incisor torque, premolar derotation, molar distalization) with 20 movements each were analyzed. The 3 movement groups were subdivided so that 10 movements were supported with an attachment and 10 were not. The patients' ClinCheck (Align Technology, Santa Clara, Calif) was planned so that the movements to be investigated were performed in isolation in the respective quadrant. Resin replicas of the patients' intraoral situation before the start of the investigated movement were taken and mounted in a biomechanical measurement system. An aligner was put on the model, the force systems were measured, and the calculated movements were experimentally performed until no further forces or moments were generated. Subsequently, the next aligners were installed, and the measurements were repeated.

Results:

The initial mean moments were about 7.3 N·mm for maxillary incisor torque and about 1.0 N for distalization. Significant differences in the generated moments were measured in the premolar derotation group, whether they were supported with an attachment (8.8 N·mm) or not (1.2 N·mm). All measurements showed an exponential force change.

Conclusions:

Apart from a few maximal initial force systems, the forces and moments generated by aligners of the Invisalign system are within the range of orthodontic forces. The force change is exponential while a patient is wearing removable thermoplastic appliances.

More Related Videos

3D Imaging of PDL Collagen Fibers during Orthodontic Tooth Movement in Mandibular Murine Model

3D Imaging of PDL Collagen Fibers during Orthodontic Tooth Movement in Mandibular Murine Model

Published on: April 15, 2021

Author Spotlight: Insights into an Efficient Murine Maxillary Orthodontic Model Protocol

Author Spotlight: Insights into an Efficient Murine Maxillary Orthodontic Model Protocol

Published on: October 27, 2023

Related Concept Videos

Resultant Moment: Scalar Formulation

Resultant Moment: Scalar Formulation

When multiple forces act on an object in two-dimensional space, the concept of the net moment can be used to understand the tendency of these forces to induce rotational motion about a fixed point. The scalar formulation of the resultant moment is a helpful tool in analyzing the equilibrium of structures subjected to multiple forces.
To determine the resultant moment, the moments caused by all the forces in a system in the x-y plane are considered. Positive moments are typically...

Bending and Torsional Moments

Bending and Torsional Moments

Bending and torsional moments are two fundamental concepts in structural engineering. They play an important role in understanding the behavior of materials and structures under different loading conditions.
The reaction developed in a structural element when subjected to an external force causes the element to bend. When a structural element bends upwards, it creates compressive normal forces on the top and tensile normal forces on the bottom, resulting in a couple that determines the bending...

Net Torque Calculations

Net Torque Calculations

When a mechanic tries to remove a hex nut with a wrench, it is easier if the force is applied at the farthest end of the wrench handle. The lever arm is the distance from the pivot point (the hex nut in this case) to the person’s hand. If this distance is large, the torque is higher. Only the component of the force perpendicular to the lever arm contributes to the torque. Therefore, pushing the wrench perpendicular to the lever arm is more advantageous. If multiple people apply force to...

Angle of Twist: Problem Solving

Angle of Twist: Problem Solving

An electric motor applies a torque of 700 N·m to an aluminum shaft, triggering a stable rotation. Two pulleys, B and C, are subjected to torques of 300 N·m and 400 N·m, respectively. The modulus of rigidity is provided as 25 GPa. With the knowledge of the length and diameter of each segment, the twist angle between the two pulleys can be computed. First, a section cut is made between pulleys B and C, and the cut cross-section is analyzed using a free-body diagram. Given that the...

Relation Between Moment of a Force and Angular Momentum

Relation Between Moment of a Force and Angular Momentum

In the realm of spinning tops, the application of force at a distance from the center produces torque, a pivotal factor that alters the angular momentum of the top, thereby inducing its rotation. The concept of moment, akin to linear force in rotation, quantifies how a force acting upon an object initiates rotational motion. Angular momentum serves as the rotational counterpart to linear momentum, representing an object's inherent tendency to persist in its rotational state.
The temporal...

Torque

Torque

Torque is an important quantity for describing the dynamics of a rotating rigid body. We see the application of torque in many ways in the world, such as when pressing the accelerator in a car, which causes the engine to apply additional torque on the drivetrain. Here, we define torque and provide a framework to create an equation to calculate torque for a rigid body with fixed-axis rotation.
Torque can be considered as the rotational counterpart to force. Since forces change the translational...

Articles linked to this work by shared authors, journal, and citation graph.

Biomechanical Evaluation of Force Loss and Simulated Tooth Movement in Maxillary Orthodontic Mesial Sliders: An In Vitro Pilot Study.

Bioengineering (Basel, Switzerland)·2026

Bicuspid aortic valve stenosis is characterized by increased angiogenesis, inflammation, and a higher valvular-to-systemic calcification ratio than tricuspid aortic valve stenosis.

Basic research in cardiology·2026

PRIFED 2026 Preferred items checklist to report finite element studies in dentistry.

Journal of the mechanical behavior of biomedical materials·2026

Internal fit and marginal adaptation of digitally fabricated interim fixed dental prostheses.

The Journal of prosthetic dentistry·2026

Transformation Temperatures and Mechanical Properties in Bending of a Multizone Rhodium-Coated NiTi Archwire: A Retrieval Analysis Study.

Journal of functional biomaterials·2026

Comparison of the biomechanical properties of CAD/CAM individualized lingual retainers: An in vitro study.

Korean journal of orthodontics·2026

See all related articles