Purpose: The primary objective was to compare canine and molar movement between NiTi coil and elastomeric chains. The secondary objective was to compare the side effects of these techniques (rotation and tipping).
Materials And Methods: This single-blind randomized split-mouth clinical trial was done prospectively. Healthy patients who needed extraction of the first maxillary premolars and did not require anchorage reinforcement techniques for orthodontic treatment were included. Following initial levelling and alignment a dental cast and panoramic radiographs were taken (pre-space closure documents) and canine retraction was done using elastomeric chains on one side and NiTi closed coil spring on the other side. After four months, the same documents were taken and movement (mm), as well as rotation (degree) and tipping (degree) of canines and first molars, were calculated by comparison of pre and post space closure documents by a blinded examiner. Data were analysed by independent samples t-test and Mann-Whitney U test with a significance level of 0.0125.
Results: Overall 20 patients completed the study. The average canine movement was 3.88 and 5.45mm (distal movement) in elastomeric chains and NiTi coil groups, respectively (P=0.001). For molars, the movement was 1.20 and 1.15mm (mesial movement), respectively (P=0.529). The mean rotation of the canine in elastomeric chains and NiTi coil groups were 4.50° and 7.43° (mesiobuccal rotation), respectively (P=0.006). For the molars, the mean rotation was 0.23° and 1.90° (mesiolingual rotation), respectively (P=0.307). Average tipping of the canine in elastomeric chains and NiTi coil groups were 4.52° and 7.55° (distal tipping), respectively (P=0.011). For the molars, the numbers were 1.45° and 4.80° (mesial tipping), respectively (P=0.028).
Conclusion: Canine retraction by NiTi coil springs is faster compared to elastomeric powerchains with the cost of more canine tipping and rotation and more molar tipping. No significant difference was found in molar movement, rotation and tipping between the two techniques.
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http://dx.doi.org/10.1016/j.ortho.2021.11.002 | DOI Listing |
Materials (Basel)
December 2024
State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
The azido propellant, with high energy and low signature, has been a hotpot in the field of propellants. However, the risk of low heat resistance and mechanical performance restricts their range of applications in high-energy formulations. In this study, four azido propellants based on 3,3-bis (azidomethyl) oxetane-tetrahydrofuran copolyether (BAMO-THF) have been prepared, their basic physical properties including energetic properties, internal micro-structure and true density were studied; their tensile properties, dynamic mechanical performances, were investigated, the structure-properties relationship was proposed.
View Article and Find Full Text PDFJ Orthod Sci
November 2024
Department of Orthodontics, College of Dentistry, University of Baghdad, Baghdad, Iraq.
Objectives: This study aimed to determine how three different energy drink types affected the force decay of three distinct brands of clear, short elastomeric chains over various time intervals.
Materials And Methods: In this study, 600 pieces of clear, short elastomeric chains from three brands were examined. The initial force was measured immediately using a digital scale and after 1, 7, 14, 21, and 28 days.
Bottlebrush polymers are complex architectures with densely grafted polymer side chains along polymeric backbones. The dense and conformationally extended chains in bottlebrush polymers give rise to unique properties, including low chain entanglement, low critical aggregation concentrations, and elastomeric properties in the bulk phase. Conjugated polymers have garnered attention as lightweight, processible, and flexible semi-conducting materials.
View Article and Find Full Text PDFBiofabrication
December 2024
Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy 502284, Telangana, India.
Bioprinting a resilient yet optically transparent corneal tissue substitute remains a challenge. In this study we introduce an innovative methodology aimed at bolstering the mechanical and optical attributes of silk fibroin (SF) hydrogels, pivotal for the progression of cornea tissue engineering. We devised a unique eosin Y-based photoinitiator system to instigate di-tyrosine linkages within highly concentrated pristine SF solutions under green light exposure.
View Article and Find Full Text PDFJ Orthod Sci
September 2024
Department of Pedodontics, Orthodontics and Prevention, College of Dentistry, University of Mosul, Mosul, Iraq.
Objectives: This study aimed to compare the force decay of the power-chain elastics after exposure to anti-coronavirus 2019 (COVID-19) antiseptic mouthwashes at different intervals.
Methods: A total of 300 power-chain pieces were used from American Orthodontics (AO) and Dentaurum (D) brands. Each piece composed of five loops that were selected to simulate canine retraction distally.
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