The Influence of Heights of Power Arm for Controlled Anterior Teeth Movement in Sliding Mechanics: A 3D FEM Study

Abstract

Introduction: The effectiveness of orthodontic treatment depends on precise control of the anterior teeth during retraction in sliding mechanics. That is why researchers were interested in finding the appropriate loading conditions for sliding mechanics to govern anterior teeth's movement, such as the height of retraction force application and its location on the arch wire. Methods: A FEM study was conducted to evaluate the type of movement of anterior teeth during en-masse retraction by applying 200 gms of force to each side of the maxillary arch with power arms set at various levels (4 mm, 6 mm, 8 mm) mesial to canine from mini-screw placed at a height of 8 mm between maxillary first molar and second premolar. A 3D model (FEM) of the maxillary arch was constructed to study the amount of labio-lingual tipping and bodily displacement of maxillary central incisor achieved. Results: When a 200-gm power was applied to the power arm, controlled lingual crown tipping was seen at the levels of 4 mm and 6 mm, in contrast to the level of 8 mm, where bodily displacement occurred, according to this evaluation. Conclusion: In sliding mechanics, the height of the power arm plays an important role in obtaining controlled lingual crown tipping or bodily displacement during retraction of anterior teeth.

Force-Controlled Biomechanical Simulation of Orthodontic Tooth Movement with Torque Archwires Using HOSEA (Hexapod for Orthodontic Simulation, Evaluation and Analysis)

“…Compared to in silico FE analysis, HOSEA allows the observation and analysis of the biomechanical properties of physical orthodontic appliances, whereas FE analyses are solely based on calculative models [ 3 , 39 ]. FE simulations calculate forces and moments generated by mechanically idealized orthodontic appliances or archwires.…”

Biomechanical Simulation of Orthodontic En-Bloc Retraction Comparing Compound Technique and Sliding Mechanics Using a HOSEA Robotic Device

“…The SS 0.017" × 0.025" archwires exhibited the highest amount of palatal tipping (|R y,max | = 19.717 • ), in contrast to the 0.018" × 0.025" RTAs, which exhibited the least amount of palatal tipping (|R y,max | = 8.535 • ) (Table 2). Both RTA groups exhibited significantly less palatal tipping compared to the SS groups, most likely because the use of power-hooks in the RTA groups allowed for force application closer to the center of resistance [6,30], while the elastic chains applied in combination with the SS archwires delivered the retractive forces at the centre of force. In summary, the RTA 0.018" × 0.025" group allowed for the most bodily en-bloc retraction.…”