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Angle Orthod. 2014 Nov;84(6):1054-61. doi: 10.2319/111913-845.1. Epub 2014 Apr 16.

Effects of third-order torque on frictional force of self-ligating brackets.

Author information

1
a  Instructor, Division of Orthodontics and Dentofacial Orthopedics, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Hokkaido, Japan.

Abstract

OBJECTIVE:

To investigate the effects of third-order torque on frictional properties of self-ligating brackets (SLBs).

MATERIALS AND METHODS:

Three SLBs (two passive and one active) and three archwires (0.016 × 0.022-inch nickel-titanium, and 0.017 × 0.025-inch and 0.019 × 0.025-inch stainless steel) were used. Static friction was measured by drawing archwires though bracket slots with four torque levels (0°, 10°, 20°, 30°), using a mechanical testing machine (n  =  10). A conventional stainless-steel bracket was used for comparison. RESULTS were subjected to Kruskal-Wallis and Mann-Whitney U-tests. Contact between the bracket and wire was studied using a scanning electron microscope.

RESULTS:

In most bracket-wire combinations, increasing the torque produced a significant increase in static friction. Most SLB-wire combinations at all torques produced less friction than that from the conventional bracket. Active-type SLB-wire combinations showed higher friction than that from passive-type SLB-wire combinations in most conditions. When increasing the torque, more contact between the wall of a bracket slot and the edge of a wire was observed for all bracket types.

CONCLUSIONS:

Increasing torque when using SLBs causes an increase in friction, since contact between the bracket slot wall and the wire edge becomes greater; the design of brackets influences static friction.

KEYWORDS:

Archwire; Friction; SEM; Self-ligating brackets

PMID:
24738791
DOI:
10.2319/111913-845.1
[Indexed for MEDLINE]

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