Analysis of resistance to sliding expressed during first order correction with conventional and self-ligating brackets: An in-vitro study

Purpose: To investigate the resistance to sliding (RS) related to self-ligating and conventional ligation bracket systems at several first order rotational angulations using typical aligning arch wires in a 3-bracket experimental model. Materials and methods: Resistance to sliding (RS) was measured in self-ligating (SL: Interactive selfligating brackets with closed slide) and conventional ligation (CL: Interactive self-ligating brackets with open slide and elastomeric ligatures) groups in conjunction with 0.014-in heat-activated NiTi (Af temp: 36°). A custom-made machine was used to measure frictional resistance with tests repeated on 5 occasions at each simulated angulation. Results: The RS increased significantly as the angulation increased in both groups (P < 0.0001). However, RS measurements were significantly higher at each angulation (P < 0.0001) with the conventional ligation system than with self-ligation. Conclusion: During simulated tooth movement with low stiffness wires, RS is increased in conventional-ligating systems particularly at higher degrees of angulation.