Transfer Accuracy of 3D-Printed Trays for Indirect Bonding of Orthodontic Brackets: A Clinical Study

Abstract

Aim: To evaluate the transfer accuracy of 3D-printed indirect bonding trays constructed using a fully digital workflow in a clinical setting.Methods: Twenty-three consecutive patients had their incisors, canines, and premolars bonded using a fully digital indirect bonding method and 3D-printed transfer trays. Intraoral scans were taken to capture the final bracket positioning on the teeth following bonding. Digital models of the post-bonding scans were superimposed on those of the corresponding virtual bracket setups, and bracket positioning differences were quantified. A total of 363 brackets were evaluated. One tailed t-tests were used to determine whether bracket positioning differences were within limits of 0.5 mm in the mesio-distal, bucco-lingual, and occluso-gingival dimensions, and within 2° for torque, tip, and rotation. Results: Mean bracket positioning differences were 0.10 mm, 0.10 mm, and 0.18 mm for mesio-distal, bucco-lingual, and occluso-gingival measurements, respectively. For the linear dimensions, frequencies of bracket positioning error within the 0.5-mm limit ranged from 96.4–100%. Mean differences were significantly within the acceptable range for these dimensions. Mean differences were 2.55°, 2.01°, and 2.47° for torque, tip, and rotation, respectively. For the angular measurements, frequencies within the 2°-limit ranged from 46.0–57.0%. The mean differences for the angular dimensions were outside the acceptable limit; however, this may have been due to limitations of the scan data. Conclusions: Indirect bonding using 3D-printed trays transfers the planned bracket position from the digital setup to the patient’s dentition with a high positional accuracy in the mesio-distal, bucco-lingual, and occluso-gingival dimensions. Questions remain regarding the transfer accuracy in the angular dimensions.