The SmartClip Self-Ligating Appliance System

With the latest designs of self-ligating brackets, statements about more efficient mechanics and shorter treatment time have been referred to partly in terms of a reduction of friction in the systems. Resistance to sliding in orthodontics has been explained in terms of classical friction, binding, and notching. The materials of the archwire-bracket-ligature system and the amount of ligation force affect classical friction. Friction as binding is influenced by bracket type, size and alloy, and wire size, shape, and alloy, which is true for both self-ligating and conventional brackets. Notching represents a permanent deformation of the wire or deformation of surface characteristics of the bracket or wire material. At this point, all motion of the archwire through the bracket ceases until mastication or other forces lift the archwire away from the bracket. Because resistance to sliding is the sum of all three components, choosing a bracket with lower classical friction results in lower overall resistance to sliding. This article will discuss the SmartClip Self-Ligating Appliance System (3M Unitek, 3M Corporate Headquarters, 3M Center, St. Paul, MN 55144-1000), which has the characteristics of previous preadjusted appliance systems, and which allows for low levels of forces during biomechanics, decreasing friction between the archwire and bracket slot and providing good 3-dimensional control.