Purpose: To assess root resorptions in patients treated with bracketless invisible appliance and straight wire appliance using cone-beam CT (CBCT).
Methods: Twenty-eight patients treated with bracketless invisible appliance (as experimental group) or straight wire appliance (as control group) were randomly selected. CBCT images were analyzed at 3 time points (pre-operation, 6 month after operation, post-operation). Root resorption was calculated using root length at 3 time points. The difference between the 2 groups was analyzed with SPSS16.0 software package. To those teeth with no root length reduction, the bone defect was evaluated using CBCT.
Results: After 6-month of treatment, 47.3% teeth from the experimental group had root resorption, while 68.3% in the control group. There was significant difference between the 2 groups (P<0.05). Root absorption of maxillary central incisors from the 2 groups was more severe than other teeth (55% in the experimental group, and 75% in the control group). After orthodontic treatment, the incidence of root resorption in the control groups increased to be 85.3% and 68.3% in the experimental group (P<0.05). To those teeth with no root resorption, bone defect was more common in the palatal side (18% in the experimental group, 14% in the control group).
Conclusions: Compared with straight wire appliance, patients using bracketless invisible appliance suffer from less root resorption.