3D-printed clear aligners: An emerging alternative to the conventional thermoformed aligners? – A systematic review

Abstract

Objectives

To assess the differences between the traditional thermoformed clear aligners (TFA) and the emerging 3D-printed clear aligners (DPA) by comparing their mechanical and chemical properties, manufacturing process, accuracy trueness and precision, and effect on sustainability. To evaluate whether 3D-printing is more efficient than thermoforming in the manufacturing of clear aligners.

Data

Data was collected from scientific articles related to 3D-printed aligners’ properties and comparative cross-referenced articles related to the thermoformed aligners’ properties.

Sources

The sources assessed to retrieve the articles were scientific databases Scopus and PubMed.

Study selection

A PICO format research question guided the study selection by both assisting in the formulation of keyword combinations and establishing a set of inclusion and exclusion criteria to meet this review's objectives.

Results

The results indicate that both aligners have good mechanical properties, but the DPA distinguished themselves with two novel properties, shape memory and design flexibility. Additionally, they exerted a consistent force profile in contrast to the TFA. The DPA have higher accuracy, trueness and precision than the TFA, however similar to the thermoforming process, direct-printing also varied the thickness of the DPA from the original master STL model. There are limited studies on sustainability and biocompatibility of the DPA.

Conclusions

Following this review, it can be concluded that 3D-printed aligners are likely to serve as an alternative to the thermoformed aligners in the near future, seeing their innovative and promising properties. However, further experimental studies with higher quality of evidence and an emphasis on randomization are necessary to confirm current laboratory-based studies’ findings and address important limitations before promoting the aligners to a larger audience.

Clinical Significance

The design flexibility of 3D-printing technology, and the shape memory property of currently marketed 3D-printed aligners could positively impact the accomplishment of precise, desired orthodontic outcomes, potentially reducing clinical treatment time.