Table 1 Inclusion and exclusion criteria

Non growing patients (skeletal age CS6 according to the cervical vertebral maturation method)

Use of auxiliaries in combination with clear aligners

Non extraction treatment

Periodontal disease

Treatment with a clear aligner system with a thickness of 0.75 mm

Implants or root canal therapies before and during the orthodontic treatment

Sequence of 15 aligners or more

Temporomandibular disorders

Moderate crowding (4–6 mm) according to the Little index

Skeletal malformations and destructive caries