Effects of reversing the coiling direction on the force-deflection characteristics of nickel-titanium closed-coil springs
박환형, Jung Suk-Hwan, Yoon Ju-Il, Jee Kwang-Koo, 한준현, 백승학,
소속 상세정보
박환형 ( Park Hwan-Hyung ) - Seoul National University School of Dentistry Department of Orthodontics
( Jung Suk-Hwan ) - Hansung University Department of Mechanical System Engineering
( Yoon Ju-Il ) - Hansung University Department of Mechanical System Engineering
( Jee Kwang-Koo ) - Korea Institute of Science and Technology Future Convergence Research Division
한준현 ( Han Jun-Hyun ) - Chungnam National University Department of Materials Science and Engineering
백승학 ( Baek Seung-Hak ) - Seoul National University School of Dentistry Department of Orthodontics
Abstract
Objective: To investigate the effects of reversing the coiling direction of nickel-titanium closed-coil springs (NiTi-CCSs) on the force-deflection characteristics.
Methods: The samples consisted of two commercially available conventional NiTi-CCS groups and two reverse-wound NiTi-CCS groups (Ormco-Conventional vs. Ormco-Reverse; GAC-Conventional vs. GAC-Reverse; n = 20 per group). The reverse-wound NiTi-CCSs were directly made from the corresponding conventional NiTi-CCSs by reversing the coiling direction. Tensile tests were performed for each group in a temperature-controlled acrylic chamber (37 ± 1°C). After measuring the force level, the range of the deactivation force plateau (DFP) and the amount of mechanical hysteresis (MH), statistical analyses were performed.
Results: The Ormco-Reverse group exhibited a significant shift of the DFP end point toward the origin point (2.3 to 0.6 mm), an increase in the force level (1.2 to 1.3 N) and amount of MH (1.0 to 1.5 N) compared to the Ormco-Conventional group (all p < 0.001), which indicated that force could be constantly maintained until the end of the deactivation curve. In contrast, the GAC-Reverse group exhibited a significant shift of the DFP-end point away from the origin point (0.2 to 3.3 mm), a decrease in the force level (1.1 to 0.9 N) and amount of MH (0.6 to 0.4 N) compared to the GAC-Conventional group (all p < 0.001), which may hinder the maintenance of force until the end of the deactivation curve.
Conclusions: The two commercially available NiTi-CCS groups exhibited different patterns of change in the force-deflection characteristics when the coiling direction was reversed.
키워드
Nickel-titanium closed-coil spring; Range of the force plateau; Force-deflection characteristics; Reversing the coiling direction
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