Bracket transfer accuracy of two three-dimensionally printed lingual indirect bonding trays with different bracket...

To compare bracket transfer accuracy of two three-dimensionally (3D) printed indirect bonding tray designs for lingual indirect bonding.

Virtual bracket placement was performed using OnyxCeph (OnyxCeph 3D Lab, Chemnitz, Germany). Tray design 1 was designed with a low bracket frame, while tray design 2 was designed with a high bracket frame. A total of 30 bonding trays and corresponding dental models were additively manufactured, 15 per design. After indirect bonding, achieved bracket positions were scanned. Linear and angular transfer errors were assessed. Statistical analysis of mean transfer errors and frequency of clinically acceptable errors (defined as < 0.5 mm and < 2°) were performed using Mann-Whitney U-test and χ2 test.

Both tray designs demonstrated comparable transfer accuracy. Linear, tip, and rotation errors were mostly within clinical limits. All linear values were acceptable, except for vertical dimension in the incisors (98.3%). Rotation accuracy was high across all tooth groups (78.9-100%). Torque showed the greatest deviations, with only 11.9% of incisor brackets in the high-frame and 75.4% in the low-frame groups within acceptable limits. Overall, torque consistently had the lowest rate of clinically acceptable outcomes across both tray designs.

Considering favorable transfer accuracy and improved handling characteristics of the low-frame tray design, its clinical application may be preferred. However, achieving high accuracy in the torque dimension remains a challenge with 3D-printed indirect bonding trays.