Randomization, allocation concealment, and blinding
Subjects were assigned into two parallel groups with a 1:1 allocation ratio by computer-generated list of random numbers. Allocation series was hidden using numbered, opaque, sealed envelopes which were opened at the premolars extraction session. First group received 3D guided piezocisison-assisted orthodontic treatment, while the second group received conventional one. Random allocation sequence generation, patient assignment to interventions,the allocation concealment and outcomes processing were assigned to one of the academic stuff at the Department of Oral and Maxillofacial Surgery(not involved in this research).However, Blinding of personnel and participants was not viable.