Abstract: Objective: To investigate the difference between eating with aligners (EWA) and eating without aligners (EWOA) on the vertical height of posterior teeth. Methods: A prospective study was performed on 60 subjects selected for treatment with invisible appliance, all of whom were treated without tooth extraction. The patients were divided into the experimental group and control group according to whether or not they wore the invisible appliance while eating, with 30 cases in the experimental group and 30 cases in the control group. The experimental group was suggested to wear the invisible appliance to eat, while the control group did not wear the invisible appliance to eat. The vertical displacement distance of the first maxillary molars (U6 and L6) and the bone changes of the upper and lower mandible were compared between two groups before and after treatment. Results: There were no significant differences between two groups in molar height, S-Go/N-Me (%), FMA(°), OP-FH(°), and MP-OP(°) before and after treatment (P>0.05). Conclusion: There was no effect on the vertical height of posterior teeth by wearing an invisible orthodontic device when eating.

Key words: invisible aligners, vertical height, mastication, molar