The bracketless invisible aligner technique has been considered as a new developed orthodontic technique since its appearance during the period of late 1990s. It is characterized with the advantages of more aesthetic, comfortable, simple, high- efficient and predictable compared with current traditional orthodontic techniques depending on brackets and wires for orthodontic tooth movements. There have been many opportunities for further development and clinical application for the technique with the developments of material sciences, computer software and hardware technology, rapid prototyping techniques, et al. Nevertheless, kinds of difficulties and challenges have been and should be met either at present or in the future for this relatively new technique which just occurred around 10 years ago. The histories, developments with opportunities and challenges and prospects of the technique will be reviewed and discussed in this paper.
