Trimline Study - Discussion

Design: The most retentive aligner margin design is a straight-line margin cut 2mm above the gingival zenith.

Retention: Straight-line margins cut at the gingival zenith (Omm) had significantly higher retentive force when compared to scalloped margins of the same material type with attachments.

Material: Invisacryl A material had significantly higher retention values when compared to Invisacryl C material with the same margin and attachment design.

Movements: Straight-line gingival margins decrease the flexibility of an RTA at the gingival margin increasing retention, the probability of accomplishing more complex movements (such as torque) and expressing a greater amount of tooth movement is increased.