engleski

MECHANICAL PROPERTIES OF ORTHODONTIC ARCHWIRES: INFLUENCE OF TYPE OF ALLOY AND SURFACE COATING

Objectives: To evaluate the effect of type of alloy and surface coating on mechanical properties of orthodontic archwires and explore which properties influence mostly sliding resistance. Materials and Methods: Four samples of four types of orthodontic archwires in dimension 0.020×0.020’’ were tested: uncoated nickel titanium (NiTi), rhodium coated (RhNiTi), nitrified (NNiTi) and stainless steel (SS). Mechanical testing included Vickers microindentation hardness analysis on Leica VMHT MOT indenter (Walter Uhl, Asslar, Germany), measurement of surface roughness using the non-contact profilometer Talysurf CLI 1000 (Taylor Hobson Ltd., Leicester, UK) and friction by means of sliding resistance in constellation of three stainless steel brackets bonded in passive configuration using dynamometer Sun 500 (Galdabini, Cardano al Campo, Italy). Results: SS has significantly lower surface roughness than all NiTi types (p<0.001) which do not differ significantly. Microhardness of SS is significantly higher than all NiTi, and RhNiTi higher than uncoated NiTi (p<0.001) but not than nitrified. Differences in friction are not significant, although SS produces the lowest and RhNiTi the highest friction. Surface roughness correlates better with microhardness (r=-0.832-(-0.835) ; p<0.001) then with friction (r=0.449-0.457 ; p<0.05) and microhardness is not significantly related to friction. Conclusions: Mechanical properties of orthodontic archwires are influenced not only by alloy type but also by coating. Friction is only partially related to surface roughness.

mechanical properties; orthodontic archwires; sliding resistance

Izrađeno i financirano u sklopu projekta “Imunosne i regenerativne implikacije korozije dentalnih materijala u djece i adolescenata” Hrvatske zaklade za znanost (IP-2014-09-7500) voditelja Stjepana Špalja