Effects of ligation type and method on the resistance to sliding of novel orthodontic brackets with second-order angulation in the dry and wet states

Rectangular stainless steel (SS) archwires were coupled with four SS bracket designs: Mini Diamond Twin, which was a conventional twin bracket; VersaT, which had bumps along the slot floor and rounded slot walls; Shoulder, which had bosses outside the tie-wings to lift the ligation off the archwire; and Synergy, which had bosses between the outer and inner tie-wings, bumps along the slot floor, and rounded slot walls. For all designs, the values of resistance to sliding (RS) were measured at five normal forces and 32 second-order angulations in the dry and wet (saliva) states. RS values at these same angles and states were also measured for the following: Mini Diamond Twin brackets ligated with rings and SS ligature wires; VersaT brackets ligated with rings; Shoulder brackets ligated with rings in a figure-8 and a figure-O around the tie-wings; and Synergy brackets ligated with rings around the outer tie-wings and around the inner tie-wings. In both states, the coefficients of friction were similar for the Mini Diamond Twin, VersaT, and Synergy brackets; the values for the Shoulder brackets were slightly greater than for the other three designs. In the passive configuration, the features of the Shoulder and Synergy brackets reduced RS when the rings were not in contact with the archwires. In the active configuration, the binding behavioral patterns of the brackets were not influenced by ligation methods. Thus, these different ligation types and methods only affected the classical frictional component of RS in the passive configuration.