British Journal of Medicine and Medical Research vol:2 issue:4 pages:597-620
Aims: The aims of this study were to investigate batch-to-batch differences in
mechanical and thermal properties of 22 commercial nickel-titanium wires and evaluate
the surface quality. Secondly the percentages of superelasticity at mouth temperature
Study Design: In vitro laboratory study.
Place and Duration of Study: Sample: Department of Oral Health Sciences –
Orthodontics and Metallurgy and Materials Engineering KU Leuven, between January
2010 and May 2011.
Methodology: The sample comprised 22 NiTi wires of the upper jaw from 7 different
manufacturers. For each brand two different batches were investigated (LOT A, LOT B).
Three different investigations were carried out. First transformation behaviour and
transition temperatures were determined by differential scanning calorimetry, second a
three point bending test was done to evaluate the mechanical properties and third
scanning electron microscopy was performed on all samples to evaluate surface quality.
Results: Absolute batch-to-batch differences in the investigated properties were all
deviating from zero, although most differences were clinically acceptable. Significant
interbatch differences in thermal properties were found in 4 wires. Mechanical interbatch
differences were found remarkable for 5 wires. Percentage of elasticity showed a non-superelastic curve below a deflection of 1500 μm, which represents clinical small
deflections. Surface topography showed also interbatch differences for 4 wires.
Conclusion: This study shows that batch-to-batch differences are obvious in each
sample. One has to be careful in the selection of archwires. Therefore more
standardized consument information should be provided.