Abstract
Abstract 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.
Highlights
During orthodontic and orthognathic therapy there are circumstances in which fixed appliance arch wires require the addition of an auxiliary that can be used for the application of traction
In order to facilitate the addition of hooks to arch wires, the manufacturers of orthodontic materials have designed crimpable hooks, which are easy to place in desired positions on ligated orthodontic or surgical arch wires
The nickel titanium compression hooks were easy to place on the wires
Summary
During orthodontic and orthognathic therapy there are circumstances in which fixed appliance arch wires require the addition of an auxiliary that can be used for the application of traction. Hooks welded or soldered to a stainless steel arch wire in desired positions may serve the same purpose, and might be preferred as they take up less interdental space between the appliance brackets. The hooks are fixed onto the wire by the use of a pair of crimping pliers. The disadvantage of these hooks is that their positional stability is influenced by Australasian Orthodontic Journal Volume 35 No 1 May 2019
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