Influence of different kinematics on stationary and dynamic torsional behavior of JIZAI nickel-titanium rotary instruments: An in vitro study

Autor: Myint Thu, Arata Ebihara, Moe Sandar Kyaw, Satoshi Omori, Keiichiro Maki, Shunsuke Kimura, Hayate Unno, Takashi Okiji
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Journal of Dental Sciences, Vol 18, Iss 3, Pp 1170-1176 (2023)
Druh dokumentu: article
ISSN: 1991-7902
DOI: 10.1016/j.jds.2022.10.005
Popis: Background/purpose: Using conventional approach to examine stationary torque of nickel-titanium rotary instruments contradicts the clinical condition, and its validity for motions involving clockwise and counterclockwise rotations is questionable. This study aimed to examine the effect of different kinematics on the torsional behavior using a JIZAI instrument (#25/.04) under stationary/dynamic test conditions using clinical torque limit settings. Materials and methods: In the stationary test, the 5-mm tip of JIZAI was fixed in a cylinder-shaped vise and rotated in continuous rotation (CR) with auto-torque-reverse, optimum-torque-reverse (OTR), or reciprocation (REC) until fracture (n = 10, each). In the dynamic test, straight and severe curved canals were instrumented with JIZAI using the single-length technique with CR, OTR, or REC (n = 10, each). The stationary torque at fracture, time to fracture (Tf), dynamic torque, and screw-in force were recorded using automated-shaping-device with torque/force measuring unit. One-way ANOVA or Kruskal–Wallis test and Mann–Whitney U test with Bonferroni correction were used for statistical analysis (⍺ = 0.05). Results: The kinematics did not influence the stationary or dynamic torques (P > 0.05); however, did influence the screw-in force in straight canals (P
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