Static and kinetic frictional forces of silica‑insert ceramic brackets with coated archwires in artificial saliva

Abstract

Background: During sliding mechanics, the frictional force (FF) is an important counterforce to
orthodontic tooth movement. The purpose of this in vitro study was to investigate the static and
kinetic FFs of S silica‑insert ceramic (SIC) brackets with Teflon‑coated (TC) and conventional S
stainless steel (SS) archwires.
Materials and Methods: The target group of this study included 80 maxillary canine 0.022 inch
slot SIC brackets. Forty SS brackets were used as the control. TC and conventional uncoated
SS archwires of different dimensions (0.016, 0.018, 0.016 × 0.022, and 0.018 × 0.025 inch)
were examined. All tests were carried out under artificial saliva injected condition. Scanning
Electron Micrographs were prepared for two samples of coated and uncoated archwires.
Analysis of variance and Tukey post hoc tests were used for statistical purposes (level of
significance P < 0.05).
Results: SIC brackets showed significantly lower levels of FFs than SS brackets. TC archwires had
greater frictional values than conventional uncoated ones. They also exhibited an unusual behavior
of increasing kinetic FFs with time. Indentation and delamination of coating were obvious under
scanning electron microscopy observations.
Conclusion: From the standpoint of friction, SIC brackets may serve well, even better than SS
brackets, in sliding mechanics. The coating layer of the archwires may delaminate and lost, causing
an impediment to tooth movement.
Key Words: Artificial, Friction, orthodontic bracket, saliva