Microhardness and Chemical Composition of Different Metallic Brackets: An In Vitro Study

Area of Science:

• Orthodontics
• Materials Science
• Biomaterials Engineering

Background:

• Metallic orthodontic brackets are crucial for dental alignment.
• Understanding bracket material properties is essential for clinical success and patient safety.
• Variations in alloys and manufacturing can affect bracket performance and biocompatibility.

Purpose of the Study:

• To compare the hardness of various metallic orthodontic brackets against human enamel.
• To determine the chemical composition and microstructure of different metallic bracket alloys.
• To evaluate the suitability of different bracket materials for orthodontic applications.

Main Methods:

• Microhardness testing was performed on 35 metallic brackets from seven manufacturers and human enamel.
• Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS) analyzed bracket chemical composition.
• Alloy analysis was conducted using Oxford Instruments Ultim Max Aztec software.

Main Results:

• Metallic bracket hardness ranged from 203 to 439 HV.
• Ti Equilibrium® brackets showed a significant hardness difference compared to other brackets and enamel (p=0.003).
• No significant hardness difference was found between stainless-steel alloy (SSa) and Cobalt-Chrome alloy (Co-Cra) brackets and enamel.

Conclusions:

• Bracket hardness is influenced by alloy composition and manufacturing processes.
• Genius®2 Metal, Empower®2, and Victory™ series brackets met orthodontic treatment requirements.
• Co-Cra brackets, with hardness comparable to enamel, present a viable alternative to SSa brackets for patients with nickel allergies.