Fig 1.
Thermoformed indirect bonding tray designs.
The working model is displayed in yellow, the soft layer in green, and the rigid layer in blue. (A) BL1: bilayer tray with a 1.0-mm inner soft liner and a 1.0-mm outer rigid shell. (B) BL2: bilayer tray with a 2.0-mm inner soft liner and a 1.0-mm outer rigid shell. (C) BL3: bilayer tray with a 3.0-mm inner soft liner and a 1.0-mm outer rigid shell. (D) SR1: single-layer 1.0-mm rigid tray.
Fig 2.
Workflow for deviation measurement.
The design file of the bracket body was aligned to the post-bonding scan. Each tooth was then aligned to its reference using only tooth-surface data, with a local bracket-based coordinate system defined at the bracket body. Deviations were obtained by expressing the target bracket in the reference tooth’s local coordinate system.
Table 1.
Baseline characteristics and clinical variables by tray group.
Table 2.
Inter-rater reliability for translational (mm) and angular (°) components (n = 100).
Fig 3.
Bland–Altman plots for inter-rater agreement across six dimensions.
A, Mesiodistal (mm). B, Buccolingual (mm). C, Vertical (mm). D, Rotation (°). E, Angulation (°). F, Torque (°).
Table 3.
Absolute bracket linear transfer deviations (mm) by tray design and tooth group.
Table 4.
Absolute bracket angular transfer deviations (°) by tray design and tooth group.
Fig 4.
Box-and-whisker plots of absolute bracket transfer deviations by tooth group and tray design.
BL1, bilayer tray (1.0-mm soft + 1.0-mm rigid); BL2, 2.0-mm soft + 1.0-mm rigid; BL3, 3.0-mm soft + 1.0-mm rigid; SR1 = single-layer 1.0-mm rigid tray.
Table 5.
Between-tray comparisons of absolute bracket-transfer deviations by tooth group and total arch.
Fig 5.
Violin and box plots of absolute bracket transfer deviations pooled across the total sample for each tray design.
BL1, bilayer tray (1.0-mm soft + 1.0-mm rigid); BL2, 2.0-mm soft + 1.0-mm rigid; BL3, 3.0-mm soft + 1.0-mm rigid; SR1 = single-layer 1.0-mm rigid tray.