Department of Orthodontics, Sri Ramchandra Institute of Higher Education and Research, PIN- 600116, Chennai, India.
Department of Applied Mechanics, Indian Institute of Technology (Madras), 600036, Chennai, India.
Evid Based Dent. 2024 Mar;25(1):53. doi: 10.1038/s41432-023-00937-w. Epub 2023 Nov 28.
The clinical effectiveness of clear aligners depends on the material properties both physical and mechanical. The purpose of this systematic review is to evaluate the physical and mechanical properties of different clear aligner materials and changes in the same during and after intra-oral use.
Search was done in five electronic databases: Pubmed, Embase, Scopus, Web of Science and Ovid individually by two reviewers. In vivo, Ex vivo and In vitro studies that evaluated the physical and mechanical properties of clear aligner materials were selected. The risk of bias assessment was performed using a modified Cochrane risk of bias tool.
From the 24 articles selected, 19 evaluated a single physical property and 23 articles evaluated a single mechanical property of clear aligner materials. All domains in the risk of bias assessment showed low risk of bias except for 'blinding of outcome' which was unclear in almost all the selected studies. Properties such as hardness, optical properties, stiffness, and yield strength were found to be different for different clear aligner materials and were found to change with thermoforming, with intra-oral aging, and in simulated intraoral conditions. Due to heterogenicity in the parameters used to assess physical or mechanical properties a meta-analysis could not be done.
Properties like hardness, color, stiffness, stress relaxation and creep behavior were different for various clear aligner materials and were found to deteriorate with thermoforming and intra-oral aging. Polyurethane-based materials have a higher level of hardness and stiffness but exhibit increased creep and stress relaxation properties.
CRD42021269597.
透明矫正器的临床效果取决于物理和机械性能。本系统评价的目的是评估不同透明矫正材料的物理和机械性能，以及在口腔内使用期间和之后的变化。
由两名评审员分别在五个电子数据库（Pubmed、Embase、Scopus、Web of Science 和 Ovid）中进行搜索。选择评估透明矫正材料物理和机械性能的体内、体外和体内研究。使用改良的 Cochrane 偏倚风险工具进行偏倚风险评估。
从选定的 24 篇文章中，有 19 篇评估了单一物理性能，23 篇评估了单一机械性能。除了“结果的盲目性”几乎所有选定的研究都不明确外，偏倚风险评估的所有领域都显示出低风险。不同透明矫正材料的硬度、光学性能、刚度和屈服强度等性能不同，并且在热成型、口腔内老化和模拟口腔内条件下会发生变化。由于评估物理或机械性能所使用的参数存在异质性，因此无法进行荟萃分析。
硬度、颜色、刚度、应力松弛和蠕变行为等性能因各种透明矫正材料而异，并且在热成型和口腔内老化过程中会恶化。基于聚氨酯的材料具有更高的硬度和刚度，但表现出更高的蠕变和应力松弛特性。
PROSPERO 注册号：CRD42021269597。
