●The Three-Phase Plan(矫正的操作三大阶段计划)
Figure : NiTi wire stays in the optimum range much longer.
· Slot size 0.018 ligature-tie bracket: The first wire could be in the stiffness range of an 0.012 NiTi. This will provide rapid alignment even with 3- to 4-mm displacements (Figure 4, below right). The next wire (6 to 8 weeks later) could be a square, superelastic wire that nearly fills the slot, such as the 0.0175 x 0.0175 heat-activated (HA) wire with a 6度torque loss (3M Unitek). While this wire is in place, evaluate all bracket positions using both visual and radiographic assessment. This evaluation will usually lead to resetting two to five brackets. If second molars were not placed, this is the time to do it.
· Slot size 0.022 ligature-tie bracket: If you use the 0.022 bracket, you will use larger wires for the alignment phase. At the University of California, San Francisco (UCSF), we recommend starting with 0.014 NiTi and proceeding to a 0.020 x 0.020 HA wire with 7度torque loss to finish the alignment phase.
· Slot size 0.018 ligation-free bracket(自锁式): Since there is no ligature to push the archwire to the base of the bracket, a square cross-section wire is not the best choice. A rectangular wire will improve rotational control, so after beginning with an 0.014 NiTi, switch at the second visit to the 0.016 x 0.025 HA (9度torque loss) to finish the alignment-phase procedures, including resets.
· Slot size 0.022 ligation-free bracket(自锁式): Again, a larger size is appropriate, with a goal of keeping force values low. Start with the 0.014 NiTi and proceed to 0.018 x 0.25 HA (15度torque loss).
· Slot size 0.018 ligature-tie bracket: For closing spaces, use the 0.0175 x 0.0175 SS archwire (6度torque loss) with closing loops bent into the arch. Alternatively, use the same archwire with closing modules such as AlastiK chain or NiTi closed-coil springs. This wire has the power to alter archform, flatten the occlusal plane, and bodily retract incisors.
· Slot size 0.022 ligature-tie bracket: UCSF residents use 0.019 x 0.025 SS wires (11度torque loss) for space closing with loops or retraction springs. Sometimes, torque adjustments are placed in the upper anteriors to ensure bodily movement.
· Slot size 0.018 ligation-free bracket: Use 0.016 x 0.025 SS, close space with closing loops or with closing spring modules.
· Slot size 0.022 ligation-free bracket: Use 0.019 x 0.025 SS as with the ligature-tie brackets.
Wire recommendations for the finishing phase are the following:
· Slot size 0.018 ligature-tie bracket: 0.0175 x 0.0175 SS (6度torque loss).
· Slot size 0.022 ligature-tie bracket: 0.019 x 0.025 SS (11度torque loss).
· Slot size 0.018 ligation-free bracket: 0.016 x 0.025 SS (9度torque loss).
· Slot size 0.022 ligation-free bracket: 0.016 x 0.022 SS (11度torque loss).
Using the 0.018 slot ligature-tie appliance, it would be:
· 0.014 NiTi
· 0.0175 x 0.0175 HA (热处理)
· 0.0175 x 0.0175 SS (不锈钢)
Using the 0.018 slot ligature-free bracket:
· 0.014 NiTi
· 0.016 x 0.025 HA
· 0.016 x 0.025 SS