Microstructural and mechanical characterization of contemporary lingual orthodontic brackets.
OBJECTIVE
To investigate the composition and the microstructural and mechanical characterization of three different types of lingual brackets.


METHODS
Incognito™ (3M Unitek), In-Ovation L (DENTSPLY GAC) and STb™ (Light Lingual System, ORMCO) lingual brackets were studied under the scanning electron microscope employing backscattered electron imaging and their elemental composition was analysed by energy-dispersive X-ray microanalysis. Additionally, Vickers hardness was assessed using a universal hardness-testing machine, and the indentation modulus was measured according to instrumented indentation test. Two-way analysis of variance was conducted employing bracket type and location (base and wing) as discriminating variable. Significant differences among groups were allocated by post hoc Student-Newman-Keuls multiple comparison analysis at 95% level of significance.


RESULTS
Three different phases were identified for Incognito and In-Ovation L bracket based on mean atomic number contrast. On the contrary, STb did not show mean atomic contrast areas and thus it is recognized as a single phase. Incognito is a one-piece bracket with the same structure in wing and base regions. Incognito consists mainly of noble metals while In-Ovation L and STb show similar formulations of ferrous alloys in wing and base regions. No significant differences were found between ferrous brackets in hardness and modulus values, but there were significant differences between wing and base regions. Incognito illustrated intermediate values with significant differences from base and wing values of ferrous brackets.


CONCLUSIONS
Significant differences exist in microstructure, elemental composition, and mechanical properties among the brackets tested; these might have a series of clinical implications during mechanotherapy.
*Biomaterials, and.
Spiros
S
Zinelis
**Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Greece.
Iosif
I
Sifakakis
***Department of Οrthodontics and Dentofacial Οrthopedics, School of Dentistry, University of Bern and.
Christos
C
Katsaros
****Department of Orthodontics and Paediatric Dentistry, Centre of Dental Medicine, University of Zurich, Switzerland theodore.eliades@zzm.uzh.ch.
Theodore
T
Eliades
D000465:Algorithms; D002857:Chromium / Q000032:analysis / Q000737:chemistry; D002858:Chromium Alloys / Q000032:analysis / Q000737:chemistry; D003300:Copper / Q000032:analysis / Q000737:chemistry; D003722:Dental Alloys / Q000032:analysis / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D055119:Elastic Modulus; D004577:Electron Probe Microanalysis; D006047:Gold Alloys / Q000032:analysis / Q000737:chemistry; D006244:Hardness; D006801:Humans; D007501:Iron / Q000032:analysis / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000032:analysis / Q000737:chemistry; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D013499:Surface Properties
D002858:Chromium Alloys; D003722:Dental Alloys; D006047:Gold Alloys; D002857:Chromium; D003300:Copper; D009532:Nickel; D007501:Iron