WIRED SCIENCE

G&H® NiTi archwires deliver the clinical expectations of extreme elasticity, consistent force, and shape memory, realized over a range of deflection.

G&H Orthodontics® is a recognized leader in manufacturing Nickel Titanium wire products. Continuous and meticulous testing of our wires ensures the high standards of performance we guarantee. State-of-the-art stress/strain testing of Nickel Titanium wire is performed employing a three-point deflection test (fig. A) with a load cell probe impacting a wire and recording the forces throughout the range from deflection to recovery. The test data (force vs. deflection) is verified on a daily basis to meet our stringent specifications.

The following steps show how a hysteresis graph demonstrates a NiTi wire fulfilling clinical expectations of elasticity, consistent force, and shape memory. (fig. B).

How a hysteresis graph demonstrates if a NiTi wire will fulfill the clinical expectations of elasticity, consistent force and shape memory.

Load cell contacts wire and begins deflection in 36°C waterbath.

shown by the Load Resistance Force (bump in the graph) between 0.5mm and 1mm deflection.

This wire is active and aggressive as it transitions from the Austenitic (increasing force) to Martensitic (constant force) state.

of Martensitic response. Engagement force is approximately 275gf as the wire is deflected from 0.6mm to 2.0mm. Desired, defined excursion of Martensitic phenomenon (constant force over a large deflection) exhibited represents properties unique to effective Superelastic Niti wire.

Peak load force of 270gf at 3.0mm deflection is consistent with force levels at the 0.6mmdeflection point during engagement.

Transitional rebound shows the wire is active and aggressive as engagement forces cease and recovery forces begin applying tooth moving force.

as Martensitic state is reentered during recovery

Tooth moving forces dissipate slightly then stabilize to ensure consistent unload to shape memory.

Full shape memory rebound occurs at 160gf ensuring continuity of effective tooth moving forces through complete shape recovery.

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