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Surface characteristics and ion leaching of 17-4 precipitation hardening stainless steel orthodontic brackets exposed to salt water and fluoride-based oral rinses Cover

Surface characteristics and ion leaching of 17-4 precipitation hardening stainless steel orthodontic brackets exposed to salt water and fluoride-based oral rinses

Open Access
|Jun 2025

Figures & Tables

Figure 1

Bracket slot (marked rectangular area) used for imaging of COR-F and COR spots.
Bracket slot (marked rectangular area) used for imaging of COR-F and COR spots.

Figure 2

Mean values and standard deviations of metal ion concentration in the test solutions. Different lower-case letters between the oral rinse groups within the bracket system imply a significant difference for the listed metal ion (P < 0.01).
Mean values and standard deviations of metal ion concentration in the test solutions. Different lower-case letters between the oral rinse groups within the bracket system imply a significant difference for the listed metal ion (P < 0.01).

Figure 3

SEM micrographs demonstrating the noticeable COR and adjacent COR-F spots of the Victory™ brackets (magnification ×500). The red circle indicates the bracket slot area used for imaging of COR-F and COR spots.
SEM micrographs demonstrating the noticeable COR and adjacent COR-F spots of the Victory™ brackets (magnification ×500). The red circle indicates the bracket slot area used for imaging of COR-F and COR spots.

Figure 4

SEM micrographs demonstrating the noticeable COR and adjacent COR-F spots of the Mini Diamond™ brackets (magnification ×500). The red circle indicates the bracket slot area used for imaging of COR-F and COR spots.
SEM micrographs demonstrating the noticeable COR and adjacent COR-F spots of the Mini Diamond™ brackets (magnification ×500). The red circle indicates the bracket slot area used for imaging of COR-F and COR spots.

Figure 5

Chemical composition of COR-F (a) and COR (b) spots of the brackets as analyzed by EDS.
Chemical composition of COR-F (a) and COR (b) spots of the brackets as analyzed by EDS.

VHN of the tested brackets at baseline and after exposure to oral rinses_

BracketsHardness
BaselineListerine™Orex™Salt water
Victory™312.76 ± 1.86a,A 301.52 ± 2.98b,A 303.9 ± 6.66b,A 312.20 ± 5.47a,A P = 0.002*
Twin Diamond™300.55 ± 2.89a,B 295.18 ± 2.84a,b,B 294.5 ± 2.32b,B 298.74 ± 4.66a,b,B P = 0.03*
P < 0.05

Materials used in the laboratory study_

MaterialCompositionManufacturerBatch No.
Victory Series™ Low Profile orthodontic bracketPrecipitation hardened 17-4 alloy [6,29,30] Fe: 70%, Cr: 15.5–17.5%, Ni: 3–5%, Cu: 3–5%, Si: <1%, Mn: <1%, C: <0.07%, P: <0.04%, S: <0.04%, Nb: <0.3%, Al: 0.67%, Others: 0.05%3M Unitek, Monrovia, CA, USALX2MH
Mini Diamond Twin™ orthodontic bracket Ormco, Glendora, CA, USA071723188
Listerine™ fluoride mouthwashWater, propylene glycol, sorbitol, poloxamer 407, sodium lauryl sulfate, eucalyptol, benzoic acid, sodium benzoate, methyl salicylate, thymol, sodium saccharin, menthol, sucralose, aroma, and sodium fluoride (220 ppm F)Johnson & Johnson, Neuss, Germany691760
Orex™ fluoride mouthwashWater, sorbitol, PEG-40 hydrogenated castor oil, glycerin, thymol, poloxamer 407, aroma, sodium methylparaben, sodium propylparaben, citric acid, cetylpyridinium chloride, sodium benzoate, sodium saccharin, and sodium fluoride (225 ppm F)Manufactured for Nahdi Medical Co. by Fushima, SL, Cantabria, Spain230241
Salt water oral rinse5.00 g of NaCl dissolved in 250 mL of distilled water (2% saline)

Mean difference and % loss of Fe2+, Ni2+, and Cr2+ ions from COR-F to COR spots of the brackets immersed in oral rinses_

Metal ionsOral rinsesVictoryMini Diamond P-value
Mean diff.SELoss (%)Mean diff.SELoss (%)
Fe2+ Listerine™45.60.571.064.80.498.0 P < 0.0001*
Orex™53.00.582.563.50.496.0 P < 0.0001*
Salt water35.70.655.635.70.954.0 P = 0.976
Ni2+ Listerine™4.50.398.24.80.499.4 P = 0.418
Orex™3.70.380.53.10.463.4 P = 0.528
Salt water3.30.372.43.00.462.6 P = 0.131
Cr2+ Listerine™14.30.886.216.10.399.0 P = 0.0238*
Orex™13.90.883.414.10.386.9 P = 0.619
Salt water4.90.829.311.70.372.2 P = 0.0002*

Surface roughness (R a in µm) of the bracket surface before and after immersion in media_

ImmersionVictory™
Listerine™Orex™Salt water
Before0.21 ± 0.02a,A 0.20 ± 0.04a,A 0.21 ± 0.01a,A P = 0.89
After0.92 ± 0.01a,B 0.93 ± 0.02a,B 0.65 ± 0.07b,B P < 0.01*
P < 0.01
Twin Diamond™
Listerine™Orex™Salt water
Before0.35 ± 0.05a,A 0.37 ± 0.04a,A 0.35 ± 0.05a,A P = 0.77
After1.23 ± 0.03a,B 1.16 ± 0.01a,B 0.76 ± 0.08b,B P < 0.01*
P < 0.01

Chemical element concentrations of the COR-F and COR spots of the brackets obtained via EDS_

Oral rinsesCrMnFeCoNi
VictoryCOR-F16.6 ± 1.41a 2.6 ± 0.20a 64.3 ± 1.01a 5.8 ± 0.58a 4.6 ± 0.68a
Listerine™2.3 ± 0.08b 0.9 ± 0.06b 8.7 ± 0.14b 0.1 ± 0.07b 0.08 ± 0.04b
Orex™2.8 ± 0.09b 0.4 ± 0.09c 1.2 ± 0.01c 0.04 ± 0.04b 0.9 ± 0.008b
Salt water11.7 ± 0.11c 0.08 ± 0.04c 18.6 ± 0.58d 0.50 ± 0.02b 1.3 ± 0.05b
Mini DiamondCOR-F16.3 ± 0.53a 3.3 ± 0.15a 66.1 ± 0.82a 5.8 ± 0.37a 4.8 ± 0.79a
Listerine™0.2 ± 0.03b 0.09 ± 0.04b 1.3 ± 0.12b 0.04 ± 0.02b 0.03 ± 0.01b
Orex™2.4 ± 0.07c 0.1 ± 0.05b 2.7 ± 0.17b 0.4 ± 0.04b 1.8 ± 0.12b
Salt water4.5 ± 0.02d 0.1 ± 0.04b 30.4 ± 1.34c 0.5 ± 0.11b 1.8 ± 0.09b
DOI: https://doi.org/10.2478/msp-2025-0023 | Journal eISSN: 2083-134X | Journal ISSN: 2083-1331
Language: English
Page range: 113 - 126
Submitted on: Feb 8, 2025
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Accepted on: Jul 20, 2025
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Published on: Jun 30, 2025
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year

© 2025 Durgesh Bangalore, Raghad Alhassoun, Samer M. Alaqeel, Omar Alsadon, Obaid A. Alshahrani, Majed M. Alsarani, Maymoonah Alsharif, Jukka Pekka Matinlinna, published by Wroclaw University of Science and Technology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.