Mechanical Properties of the Ni-Ti Memoria® Leaf Spring Activated Expander

Objectives: To determine the mechanical properties of the Ni-Ti Memoria ® Leaf Spring Activated Expander (Ni-Ti MLSAE) by assessing compression and expansion forces.
Methods: An in-vitro pilot study was conducted using four Ni-Ti MLSAE expanders (American Tooth Industries, Oxnard, California) with a 10mm expansion screw size. A Dillion Quantrol 500N/110lbf universal testing machine was used to determine the amount of expansive force displayed. Each expander was connected to the supports of the universal testing machine. The appliances with the Ni-Ti leafs were then fully compressed and the Ni-Ti MLSAE screws were allowed to expand to their original form. The compression and expansion forces were then measured using the Emperor™ (Force) Software.
Results: The mean expansion force was found to be 897.35 grams (8.8N). This maximum force may only be expressed when the appliance is fully compressed.
Conclusions: The forces generated by the Ni-Ti MLSAE correlate with the benchmark studies conducted by the manufacturer (900grams).