Table 1 Inclusion and exclusion criteria

• Adult subjects > 18 years with permanent dentition

• Complete dentition, or with 4 missing teeth at the most (third molars excluded)

• No supernumerary teeth

• No tooth shape anomalies

• No dental rotation > 35°

• No diastems > 5 mm

• Crowding < 5 mm per arch

• Systemic pathologies

• Ongoing pharmacological treatment able to influence orthodontic movement (e.g. prostaglandin inhibitors, biphosphonates)

• Active periodontal disease

• Treatments requiring extraction space closure