Second order root control of self-ligating brackets and traditional brackets: a "typodont" study

Area of Science:

• Orthodontics
• Biomaterials Science

Background:

• Self-ligating brackets (SLB) are designed to reduce friction compared to conventional brackets (CB).
• Understanding root control is crucial for predictable orthodontic outcomes, especially during extraction space closure.

Purpose of the Study:

• To compare the second-order root control of SLB versus CB during extraction space closure.
• To evaluate the influence of different stainless steel archwire sizes (0.018 and 0.016x0.022) on root control.

Main Methods:

• A typodont model with resin teeth and anatomic roots was used.
• CB and SLB were applied to contralateral sides of the upper arch, with 20 pairwise runs conducted.
• Digital radiography and metallic markers assessed second-order root control before and after space closure with NiTi coils.

Main Results:

• On 0.018 wires, CB showed a mean root control angle of 14.8° (SD 9.15°) and SLB showed 11.8° (SD 5.01°).
• On 0.016x0.022 wires, CB had a mean root control angle of 9.7° (SD 5.48°) and SLB had 10.7° (SD 3.92°).
• Tooth movement distances were similar between CB and SLB for both wire types.

Conclusions:

• Both CB and SLB exhibit similar efficiency in crown movement during space closure.
• The degree of second-order root control is comparable between CB and SLB for both tested archwire dimensions.