Effect of Surface Treatment on Physical and Mechanical Properties of Nickel-Titanium Orthodontic Archwires by Fine Particle Shot Peening Method

Abstract

Surface treatment on metal can alter physical and mechanical properties. Understanding the physical and mechanical properties of the archwires is essential for the management of orthodontic treatment. Methods: This study used digital micrometer, universal testing machine, and surface hardness tester for measuring dimension, unloading force, and surface hardness of two different type of nickel-titanium (Ni-Ti) archwires: commercially available Ni-Ti (NT-N) and surface treated Ni-Ti by fine particle shot peening (FPSP) method (NT-F). Statistical analysis was undertaken using a paired T-test (α=0.05). Results: No significant difference was found on both vertical and horizontal dimensions of NT-N and NT-F (p= 1.00 and 0.796 respectively). For bending and surface hardness test, significance difference was found (p<0.001 and p<0.001 respectively). Conclusions: The NT-F archwire provided lower unloading force and surface hardness but there was no change in size when compared with NT-N.