Influence of long-term in vivo exposure, debris accumulation and archwire material on friction force among different types of brackets and archwires couples.
OBJECTIVE
The aim was to assess the influence of long-term in vivo exposure, debris accumulation and archwire material on static and kinetic friction force among different types of brackets and archwires couples.


METHODS
Friction testing was performed among four lower incisors' brackets, conventional and self-ligating (SL), coupled with either nickel-titanium or stainless steel archwires, as-received and in vivo exposed in 18 subjects. The friction testing was performed for a sliding distance of 14 mm at a speed of 10 mm/min, with a starting force of 0.2 N. Wear and quantitative assessment of debris accumulation was performed on pictures of brackets obtained using a scanning electron microscope. Non parametric tests were used for statistical analysis.


RESULTS
Only bracket type, but not exposure duration, amount of debris accumulation, archwire material or their manufacturer, was significantly correlated with both static (rho = 0.602, P < 0.001) and kinetic (rho = 0.584, P < 0.001) friction force. Within each bracket type no significant difference was observed between as-received and in vivo exposed brackets for any friction parameter except for the SL brackets in which significantly higher static and kinetic (P = 0.001, at least) friction forces were seen in in vivo exposed SL brackets (164.9 cN and 217.63 cN, respectively) in comparison with as-received SL brackets (19.69 cN and 55.72 cN, respectively).


CONCLUSIONS
The frictional testing was performed in the dry condition which might have influenced the results.


CONCLUSIONS
A significant correlation was seen between friction force and bracket type, while treatment duration, amount of debris accumulation, archwire material or their manufacturer was not significantly correlated to it. Nevertheless, higher friction forces were measured among in vivo aged SL brackets in comparison with as-received ones.
Beli Medved d.o.o., Radovljica, Slovenia.|Department of dental and jaw orthopaedics, University of Ljubljana, Ljubljana, Slovenia.
Uroš
U
Mezeg
Department of dental and jaw orthopaedics, University of Ljubljana, Ljubljana, Slovenia.
Jasmina
J
Primožic
D003722:Dental Alloys; D003799:Dental Stress Analysis / Q000379:methods; D017276:Friction; D006801:Humans; D008422:Materials Testing / Q000379:methods; D008855:Microscopy, Electron, Scanning; D009532:Nickel; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013193:Stainless Steel; D013499:Surface Properties; D014025:Titanium
D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium