Objectives: This in-vitro study investigated the effects of ligation and repeated vertical displacement forces on sliding resistance and the magnitude of displacement required to overcome classical friction in a multi-bracket model. Methods: Initial assessment of minimum amount of force required for continuous free sliding (f-m) for each set of archwire, bracket and ligation combination was determined. Two stainless steel brackets, 0.018”x0.025” (mini-diamond, Ormco and In-ovation, self-ligating brackets GAC); three methods of ligation (elastomeric modules, ligature ties, Co-Cr clips of the self-ligating brackets); and one stainless steel archwire (0.016”×0.022”, Ormco) were employed in this study. The f-m was reduced to 80% and applied as the sliding force. Vertical displacement forces of 50g, 100g, 150g, 200g were applied to the arch wire at the rate of 91 cycles/min to simulate intra-oral mastication. Any wire movement was attributed to decrease in resistance to sliding caused by the vertical displacement. Results: F-m values demonstrated statistically significant differences (p< 0.01) between the combinations of bracket, archwire and ligation. Self-ligating brackets offered the least resistance to sliding, followed by stainless steel brackets with ligature tie. Stainless steel brackets with elastomeric modules demonstrated the highest resistance to sliding. Ligature ties undone a quarter turn demonstrated a 37% decrease in resistance to sliding. Repeated vertical displacements have a significant effect (p< 0.001) on classical friction at the archwire/bracket interface. The reduction in sliding resistance depended on the displacement loads applied. The 50g load demonstrated the least resistance to sliding. Greater loads of 100g, 150g and 200g showed an increase in resistance to movement by 34%, 48% and 64% respectively. Conclusion: Method of ligation plays an important role on friction. Vertical displacements of the archwire reduce classical friction in-vitro provided ligation forces do not bind the archwire to the bracket slot.