Does Trimline matter in Aligners?

Straight extended trimline in CAT has been shown to be biomechanically effective across various types of tooth movements (as it’s closer to the CoR).

Higher trimline could be necessary for complex movements such as translation and root movements.

Higher trimline also showed less mandibular incisor proclination and mesial tip of the mandibular molars in class II elastic traction

Maxillary arch expansion with high trimline shows less undesirable buccal tipping of molars compared to those with low trimlines

Disadvantages of high trimlines (case selective) patients with:

• Gingival recession

• Cervical abfraction

• Black triangles

• Severe dental proclination

Have much higher discomfort during aligner removal

High trimlines may also not be suitable for periodontal patients

Higher trimline requires more accurate scanning of the gingiva.