Dynamic behavior and surface characteristics of conventional and self-ligating brackets

Abstract

ObjectiveThe purpose of this study is to compare, in vitro, the resistance to sliding generated by conventional, active self-ligating and passive self-ligating brackets with stainless steel and nickel-titanium wires and to evaluate the effects of binding. Moreover, the influence of bracket slot surface roughness on friction was estimated. MethodsConventional, active and passive self-ligating brackets were coupled with 0.016in.×0.022in. stainless steel or nickel-titanium archwires at 0° or 5° of tipping for evaluating maximum resistance to sliding. An optical 3-dimensional micro coordinate system was used to assess roughness characteristics of slot surface. Resistance to sliding data was subjected to Kruskal–Wallis, Mann–Whitney and Student's t-test (α=0.05). Spearman correlation was performed to statistical dependence evaluation. ResultsStatistically significant higher resistance to sliding is observed in conventional brackets comparing to self-ligating brackets. No statistically significant differences were found between passive and active types and between archwire alloys at 0° angulations. At 5°, stainless steel showed statistically significant higher resistance to sliding. No statistically significant differences were found between 0° and 5° of bracket tipping. The correlation between surface roughness and resistance to sliding was not statistically significant. ConclusionsSelf-ligating brackets appear to have an advantage regarding low frictional forces comparing to conventional brackets. Slight bracket angulations or tooth tipping may not have a significant influence on resistance to sliding although different alloys may exhibit dissimilar frictional behavior. It remains unclear if developing smooth slot surfaces should be a concern for manufacturers.