Gomez et al. 2018 published an FEA study to study bodily movement with aligners with and without composite attachments.

• Two FE models were constructed one with composite attachments and a second model without.

Results:

• Displacement in the FE model with no attachment caused typical uncontrolled distal crown tipping

• Displacement in the FE model with composite attachment caused distal bodily movement

Conclusions:

• Presence of composite attachmentshelp produce a counter momentresulting in more bodily movement and less tipping.

• When considering bodily movements for aligners should consider having an attachment or uncontrolled tipping may happen.

Limitations of current FE model lies in:

• the patented information of polymermaterial by aligner companies,

• difficulty in taking into consideration occlusal forces from functional and parafunctional habits and

• the replication of predetermined mismatch between aligner and tooth interface.