| Objective. To evaluate the frictional behaviour of six self-ligating bracket systems with three stainless steel archwires under dry conditions that allow the tooth to move freely during retraction. Methods. The resistances to sliding of six different self-ligating brackets (SPEED(TM), In-OvationRTMC, Carriere(TM)SLB, Clarity(TM)SL, SmartClip(TM), VisionLP(TM)) were measured with three stainless steel wires of rectangular cross-section (0.017" x 0.022", 0.017" x 0.025" and 0.019" x 0.025"), using a custom testing assembly and a universal testing machine (Instron Inc., Canton, MA). Statistical analysis was performed using a two-way, balanced ANOVA. Results The four passive self-ligating brackets (Carriere(TM)SLB, Clarity(TM)SL, SmartClip(TM), VisionLP(TM)) displayed significantly less frictional resistance (p<0.001) when compared to the remaining brackets that possess an active (SPEED(TM)), or so called Inter-active(TM) (In-OvationRTMC) clip. The SPEED(TM) bracket consistently demonstrated the highest resistance to sliding. Conclusions. The mode of self-ligation appears to significantly affect the frictional behaviour of orthodontic brackets. Passive self-ligation mechanisms generate significantly lower frictional resistance to sliding. With regard to the resistance of active self-ligating brackets, the depth of the wire had a more significant influence than its height. |
