Effect Of Ageing Treatment On Force-Deflection Behaviour Of NiTi Wire In Three-Point And Three-Bracket System
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Date
2022-07-24
Authors
Shamsul Khair, Nurul Syifa’
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
NiTi archwires used for levelling and alignment of the teeth are required to have a good
operating range that can provide light and constant force applied to the teeth. During
the teeth levelling phase of orthodontic treatment, a rectangular superelastic NiTi
archwire is usually used due to its ability to transmit torque and align the position of
tooth. However, rectangular archwire can only be applied after round wire has levelled
the teeth to a certain extent. This is due to the high stiffness and high torque that is
produced by rectangular wire. This study was designed to investigate the effect of
ageing treatment on the force-deflection behaviour of superelastic NiTi wire bent in
three-point and different interbracket settings. In this case, three-point bending was first
conducted to measure the bending deformation of 0.016 × 0.022-inch of rectangular
superelastic NiTi archwires bent after being aged at various temperatures with different
durations. Subsequently, bending in a three-bracket system was performed using aged
wires with the lowest unloading force for each ageing duration, which were selected
based on the data from three-point bending test. Findings of the study revealed that the
bending force generated by the NiTi archwire during the unloading cycle was
effectively lowered by the ageing treatment. The plateau slope, which depicts the force
constancy of the wire, considerably differed between as-received and aged wires.
During three-point bending, ageing setting of 490 °C at 45 minutes exerted the lowest
unloading forces (1.72 N) whereas as-received wire produced 2.99 N. In the three-bracket system, the least force magnitude was yielded by wires aged at 490 C for 45
minutes with 11 to 33% force reduction as compared to as-received wires. Ageing
parameter with the best constant force delivery in three-bracket bending is produced at
460 C for 35 minutes. It was also observed that flat force plateaus were produced
during the unloading when archwires were employed in wide interbracket distance,
which are 8.5 and 9.0 mm. The ageing treatment approach may be utilised to further
adjust the superelastic NiTi arch wire's deformation behaviour so that it will exert the
appropriate amount of force during tooth levelling treatment.