Figure 1.
A, Construction of orthodontic models of mandibular anterior alveolar bone of different heights. (a) Alveolar bone not resorbed. (b) Alveolar bone absorbed by one third. (c) Alveolar bone resorbed by a half. B, Experimental conditions. Conditions 1−9: the effect of lever arm length (extended between lateral incisor and canine, conditions 1, 4 and 7: 2 mm, conditions 2, 5 and 8: 7 mm, conditions 3, 6 and 9: 12 mm, respectively).
Table I.
Materials properties
| Material | Young’s modulus (MPa) | Poisson’s ratio |
|---|---|---|
| Tooth | 2.0E + 04 | 0.3 |
| PDL | 6.8E-02 | 0.45 |
| Alveolar bone | 1.3E + 04 | 0.3 |
| Bracket | 2.0E + 05 | 0.3 |
| Arch wire | 2.0E + 05 | 0.3 |
Figure 2.
Landmarks for the assessment of displacement.
Figure 3.
Total displacement trend of the lower teeth under different conditions.
Figure 4.
Displacement of the lower tooth crown (C) and root (R) in the sagittal direction and crown (C) in the vertical direction under different working conditions (mm).
Figure 5.
The von Mises stress distribution in the PDL under different conditions (Mpa).