The resistance to axial dislodgement of nickel titanium compression arch wire hooks – an in vitro study
Publié en ligne: 20 juil. 2021
Pages: 21 - 26
Reçu: 01 juil. 2018
Accepté: 01 mars 2019
DOI: https://doi.org/10.21307/aoj-2020-029
© 2019 Agneta Linder-Aronson Karsten et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.
Objective
To evaluate the level of force required to axially dislodge nickel titanium compression hooks (Trillium Compression HookTM, Hespeler Orthodontics) placed on orthodontic arch wires in vitro.
Materials and methods
Nickel titanium compression hooks were placed on arch wires with a specially designed pair of pliers. The resistance to axial dislodgement was tested on a total of 260 hooks placed in a standardised way on round (0.016″, 0.018″, 0.020″), square (0.020 × 0.020″) and rectangular (0.016 × 0.022″, 0.019 × 0.025″, 0.021 × 0.025″) stainless steel (Rocky Mountain Orthodontics), nickel titanium, or β-titanium (Hespeler Orthodontics) arch wires. The forces required to displace the hooks were recorded using an Instron tensile testing machine. The data were compared with the results reported in similar studies on stainless steel crimpable arch wire hooks.
Results
The forces required to dislodge the compression hooks varied between 45.0 N and 161.9 N. The hook’s resistance to dislodgement was found to be high in all tested hook/wire combinations. The lowest recorded average dislodging force was found in the 0.020″ nickel titanium group and the highest average force was in the 0.016 × 0.022″ β-titanium group.
Conclusion
The forces needed to dislodge the tested nickel titanium compression arch wire hooks exceed the force levels previously reported for stainless steel crimpable arch wire hooks.