Corrosion in Haas expanders with and without use of an antimicrobial agent: an in situ study

Abstract

ObjectivesThe purpose of this study was to evaluate in situ the occurrence of corrosion in the soldering point areas between the wire, silver brazing and band in Haas expanders. Material and MethodsThirty-four 7-12-year-old patients who needed maxillary expansion with a Haas expander were randomly assigned to two groups of 17 individuals each, according to the oral hygiene protocol adopted during the orthodontic treatment: Group I (control), toothbrushing with a fluoride dentifrice and Group II (experimental), toothbrushing with the same dentifrice plus 0.12% chlorhexidine gluconate (Periogard®) mouthrinses twice a week. The appliances were removed after approximately 4 months. Fragments of the appliances containing a metallic band with a soldered wire were sectioned at random for examination by stereomicroscopy, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Data were analyzed statistically by Fisher's test at 5% significance level. ResultsThe analysis by optical microscopy revealed areas with color change suggestive of corrosion in the soldering point areas joining the band and the wire in all specimens of both groups, with no statistically significant difference between the groups (p=1). The peaks of chemical elements (Ni, Fe, Cr, O, C and P) revealed by EDS were also similar in both groups. Conclusion: Color changes and peaks of chemical elements suggestive of corrosion were observed in the soldering point areas between the wire, silver brazing and band in both control and experimental groups, which indicate that the 0.12% chlorhexidine gluconate mouthrinses did not influence the occurrence of corrosion in situ.

Mapping chemical elements on the surface of orthodontic appliance by SEM-EDX

“…These can be Fe 2 O 3 (or hydrated forms), Fe 3 O 4 , FePO 4 , Fe(OH) 3 , or Cr(OH) 3 [18,23–25]. Similar results were obtained by Menezes et al during a study of bracket surfaces made of stainless steel after 60-day incubation in a physiological saline solution [22].…”

Metal ion release from silver soldering and laser welding caused by different types of mouthwash

“…4,16,19 In order to evaluate the net corrosion of the welded or the soldered parts, the whole appliance was not tested in this study.…”

“…In previous studies, 2,4,5,16,19,29 the metal ion release from different types of orthodontic appliances in various solutions was examined for different time periods. In our study, corrosion was evident after the first 24 hours.…”

“…This is considered a consequence of the release of the trace amounts of silver and copper present in some commonly used solutions, tubes, bottles, bottle caps, and clips. Although there are several studies that have investigated corrosion on orthodontic appliances caused by mouthwashes, 19,[28][29][30] there are not many studies that have investigated the effects of mouthwashes on different soldering applications. Our finding is that the greatest amount of metal ion release occurs in NaF + alcohol containing mouthwashes and may contribute to both the literature and to clinical practice.…”

“…[10][11][12][13][14][15][16][17][18] Sestini et al 18 noted that laser welding was the only well-tolerated bonding method, whereas silver soldering was highly toxic to all types of cells. Bagatin et al 19 used scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy in an in vivo study in which they investigated the corrosion of silver soldered Haas expanders in patients using antimicrobial agents. They found that the amount of metal ions increased in areas of corrosion, especially in regions where soldering was performed.…”