Comparison surface characteristics and chemical composition of conventional metallic and Nickel-Free brackets

Abstract

This study aims at comparing conventional and nickelfreemetal bracket surface characteristics with elemental compositionby scanning electron microscopy (SEM), using energy dispersivespectroscopy (EDS). The sample consisted of 40 lower incisor bracketsdivided into four groups: ABZ = conventional brackets, Kirium Abzil3M® (n = 10); RL = conventional brackets, Roth Light Morelli® (n = 10);NF = nickel-free brackets, Nickel-Free Morelli® (n = 10); and RM = nickel-freebrackets, Roth Max Morelli® (n = 10). Qualitative evaluation of the bracketsurface was performed using SEM, whereby surface features weredescribed and compared. The elemental composition was analyzedby EDS. According to surface analysis, groups ABZ and RL showed ahomogeneous surface, with better finishing, whereas the surfaces ingroups NF and RM were rougher. The chemical components with thehighest percentage were Fe, Cr and C. Groups NF and MR showed nonickel in their composition. In conclusion, the bracket surface of theABZ and RL groups was more homogeneous, with grooves and pores,whereas the surfaces in groups NF and RM showed numerous flaws,cracks, pores and grooves. The chemical composition analysis confirmedthat the nickel-free brackets had no Ni in their composition, as confirmedby the manufacturer’s specifications, and were therefore safe to use inpatients with a medical history of allergy to this metal