Influence of the cross-section of orthodontic wires on the surface friction of self-ligating brackets

|Roberta Buzzoni|Carlos N. Elias|Daniel J. Fernandes|José Augusto M. Miguel|

Objectives: The purpose of this study was to assess the surface friction produced between selfligating stainless steel brackets equipped with a resilient closure system and round and rectangular orthodontic wires made from the same material. Methods: Thirty maxillary canine brackets were divided into six groups comprising Smartclip and In-Ovation R self-ligating brackets, and conventional Gemini brackets tied with elastomeric ligatures. This investigation tested the hypothesis that self-ligating brackets are susceptible to increases in friction that are commensurate with increases and changes in the cross-section of orthodontic wires. Traction tests were performed with the aid of thirty segments of 0.020-in and 0.019 x 0.025-in stainless steel wires in an EMIC DL 10000 testing machine with a 2N load cell. Each set of bracket/wire generated four samples, totaling 120 readings. Comparisons between means were performed using analysis of variance (one way ANOVA) corrected with the Bonferroni coefficient. Results and conclusion: The self-ligating brackets exhibited lower friction than conventional brackets tied with elastomeric ligatures. The Smartclip group was the most effective in controlling friction (p<0.01). The hypothesis under test was con- firmed to the extent that the traction performed with rectangular 0.019 x 0.025-in cross-section wires resulted in higher friction forces than those observed in the 0.020-in round wire groups (p<0.01). The Smartclip system was more effective even when the traction produced by rectangular wires was compared with the In-Ovation R brackets combined with round wires (p<0.01).

Keywords: Brackets. Orthodontic wires. Stainless steel. Friction.

Tuesday, October 17, 2017 16:50