Qualitative and Quantitative Evaluation of Different Types of Orthodontic Brackets and Archwires by Optical Microscopy and X-ray Fluorescence Spectroscopy

Danilo D’Andrea,Dario Santonocito,Fabiana Nicita,Dario Milone,Giacomo Risitano

doi:10.3390/prosthesis3040031

Abstract

The wear behaviour and chemical composition of orthodontic components influence the mechanical characteristics of a fixed orthodontic treatment. The purpose of this paper is to evaluate the surface alterations of different types of brackets (aesthetic, metallic, and conventional self-ligating) and archwires (superelastic and thermal) subjected to wear tests through optical microscopy and, subsequently, to identify the chemical elements of accessories by X-ray fluorescence. The cycles (5000 for each bracket and 10,000 for each wire) of the tribological test were carried out in dry conditions inside a machine that allows alternating sliding. The results of the study highlighted different wear behaviours even within the same type of brackets and archwires. The monocrystalline sapphire brackets maintain their aesthetic properties despite traces of wear inside the slots and contain minimal amounts of nickel. Superelastic NiTi archwires have a better overall rating than thermal wires, as they do not show significant surface wear alterations.

Highlights

Friction is the resistance to movement during sliding when an object moves tangentially against another; wear occurs whenever a surface is exposed to another surface, resulting in a removal of material through mechanical action [1]
The scores reported in the following tables are based on the overall evaluation regarding the traces of wear and the release of chemical elements
The Radiance bracket reported general wear along the contact slot, with a higher concentration of material removed along the external walls of the slot

Summary

Introduction

Friction is the resistance to movement during sliding when an object moves tangentially against another; wear occurs whenever a surface is exposed to another surface, resulting in a removal of material through mechanical action [1]. Wear processes of materials, such as abrasion and corrosion, cause deterioration of materials and release of elements into the oral environment [2]. The choice of metal materials has been a long concern of biomaterial science, because it is mainly influenced by corrosion. These materials can hardly be tolerated in the oral cavity due to the poor biocompatibility of their corrosion products [5]. Friction between traditional brackets and archwires can cause various problems, such as release of toxic chemical elements, periodontal lesions, and dental root resorptions [6]

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Conclusion