Table 1
Materials used in the laboratory study.
| Material | Composition | Manufacturer | Batch No. |
|---|---|---|---|
| Victory Series™ Low Profile orthodontic bracket | Precipitation 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, USA | LX2MH |
| Mini Diamond Twin™ orthodontic bracket | Ormco, Glendora, CA, USA | 071723188 | |
| Listerine™ fluoride mouthwash | Water, 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, Germany | 691760 |
| Orex™ fluoride mouthwash | Water, 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, Spain | 230241 |
| Salt water oral rinse | 5.00 g of NaCl dissolved in 250 mL of distilled water (2% saline) | ||
Key: ppm F− = parts per million of fluoride.
Figure 1
Bracket slot (marked rectangular area) used for imaging of COR-F and COR spots.
Table 2
VHN of the tested brackets at baseline and after exposure to oral rinses.
| Brackets | Hardness | ||||
|---|---|---|---|---|---|
| Baseline | Listerine™ | 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 | |||||
*Statistically significant (P < 0.01).
Different lower-case letters between the oral rinse groups for the bracket system implies significant difference in R a between them (P < 0.01).
Different upper-case letters between the bracket groups implies significant difference in R a before and after immersion (P < 0.01).
Table 3
Surface roughness (R a in µm) of the bracket surface before and after immersion in media.
| Immersion | Victory™ | |||
|---|---|---|---|---|
| Listerine™ | Orex™ | Salt water | ||
| Before | 0.21 ± 0.02a,A | 0.20 ± 0.04a,A | 0.21 ± 0.01a,A | P = 0.89 |
| After | 0.92 ± 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 | ||
| Before | 0.35 ± 0.05a,A | 0.37 ± 0.04a,A | 0.35 ± 0.05a,A | P = 0.77 |
| After | 1.23 ± 0.03a,B | 1.16 ± 0.01a,B | 0.76 ± 0.08b,B | P < 0.01* |
| P < 0.01 | ||||
*Statistically significant (P < 0.01). Different lower-case letters between the oral rinse groups within the bracket system implies significant difference in Ra between them (P < 0.01).
Different upper-case letters between the brackets groups implies significant difference in Ra before and after immersion (P < 0.01).
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).
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.
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.
Table 4
Chemical element concentrations of the COR-F and COR spots of the brackets obtained via EDS.
| Oral rinses | Cr | Mn | Fe | Co | Ni | |
|---|---|---|---|---|---|---|
| Victory | COR-F | 16.6 ± 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 water | 11.7 ± 0.11c | 0.08 ± 0.04c | 18.6 ± 0.58d | 0.50 ± 0.02b | 1.3 ± 0.05b | |
| Mini Diamond | COR-F | 16.3 ± 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 water | 4.5 ± 0.02d | 0.1 ± 0.04b | 30.4 ± 1.34c | 0.5 ± 0.11b | 1.8 ± 0.09b |
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 5
Chemical composition of COR-F (a) and COR (b) spots of the brackets as analyzed by EDS.
Table 5
Mean difference and % loss of Fe2+, Ni2+, and Cr2+ ions from COR-F to COR spots of the brackets immersed in oral rinses.
| Metal ions | Oral rinses | Victory | Mini Diamond | P-value | ||||
|---|---|---|---|---|---|---|---|---|
| Mean diff. | SE | Loss (%) | Mean diff. | SE | Loss (%) | |||
| Fe2+ | Listerine™ | 45.6 | 0.5 | 71.0 | 64.8 | 0.4 | 98.0 | P < 0.0001* |
| Orex™ | 53.0 | 0.5 | 82.5 | 63.5 | 0.4 | 96.0 | P < 0.0001* | |
| Salt water | 35.7 | 0.6 | 55.6 | 35.7 | 0.9 | 54.0 | P = 0.976 | |
| Ni2+ | Listerine™ | 4.5 | 0.3 | 98.2 | 4.8 | 0.4 | 99.4 | P = 0.418 |
| Orex™ | 3.7 | 0.3 | 80.5 | 3.1 | 0.4 | 63.4 | P = 0.528 | |
| Salt water | 3.3 | 0.3 | 72.4 | 3.0 | 0.4 | 62.6 | P = 0.131 | |
| Cr2+ | Listerine™ | 14.3 | 0.8 | 86.2 | 16.1 | 0.3 | 99.0 | P = 0.0238* |
| Orex™ | 13.9 | 0.8 | 83.4 | 14.1 | 0.3 | 86.9 | P = 0.619 | |
| Salt water | 4.9 | 0.8 | 29.3 | 11.7 | 0.3 | 72.2 | P = 0.0002* | |
*A statistically significant difference in the mean difference of the respective metal ions between the bracket types for the oral rinses groups (paired t-test; P < 0.05).