Effects of various coating methods on the mechanical, physical, and aesthetic properties of GUMMETAL® archwires: In vitro study

Abstract

The objective of this study was to evaluate the mechanical, physical, and aesthetic properties of GUMMETAL® (GM) orthodontic archwires after the application of various aesthetic coating materials. This in vitro study included 180 orthodontic wires: five experimental groups used 0.016×0.022-inch GM as the core-based wire followed by the application of epoxy, polytetrafluoroethylene (PTFE), clear ceramic, white ceramic, or silicone; and four control groups: 0.016×0.022-inch GM, 0.019×0.025-inch GM, 0.016×0.022-inch stainless steel (SS), and 0.019×0.025-inch SS. Frictional forces, force deflection rate, yield strength, aesthetic colour value, corrosive and wear resistance were compared between the experimental and control groups. Among the coated wires, white ceramic exhibited the highest frictional force (2.06±0.20N) and silicone showed the lowest values (0.88±0.12N). There were significant differences in static friction between experimental and control groups (P<0.001). PTFE coating had the highest force deflection rate (9.03±0.12N/mm) and yield strength (10.0±0.14N/mm) among coated wires and white ceramic exhibited the lowest values (6.86±0.14N/mm and 7.74±0.17N/mm for force deflection rate and yield strength, respectively). Differences in force deflection rate and yield strength between experimental and control groups were statistically significant (P<0.001). All coated wire groups had a clinical difference in colour when compared to A1 shade. Coated and uncoated wires showed good corrosion resistance after one week in corrosive saliva with no detectable loss of mass. This study has shown that coating wires can improve some aspects of the wire properties but not all when compared to uncoated GM and SS. Future investigation of the materials used in this study is required to further characterize their properties.