IRCT20210927052606N1 IRCT 2021-10-25 Tabriz University of Medical Sciences Comparison of the effect of traditional and clear twin block on the speech of skeletal class II patients Comparison of the effect of traditional and clear twin block on the speech of skeletal class II patients 2021-10-16 anticipated 18 Complete https://irct.ir/trial/59138 interventional Randomization: Randomized, Blinding: Single blinded, Placebo: Not used, Assignment: Parallel, Purpose: Supportive, Randomization description: simple randomization method will be used and, groups assingments will be determined by flipping coin, Blinding description: Participants do not know about the allocation of study groups. What device each patient receives is selected randomly by another person without their knowledge. The patient is not aware that he is in the case or control group, but the researchers are aware. N/A class II malocclusion. Intervention 1: Intervention group: The group that receives the clear twin block appliance. This device should be used by the patient at all times except when eating and brushing. Intervention 2: Control group: The group that receives the traditional twin block appliance. This device should be used by the patient at all times except when eating and brushing. No - There is not a plan to make this available Justification or reason for not sharing IPD is no more information.