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


METHODS
Thirty-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.


RESULTS
The 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.


CONCLUSIONS
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.
Department of Pediatric Clinics, Preventive and Community Dentistry, Ribeirão Preto Dental School, University of São Paulo, Ribeirão Preto, SP, Brazil.
Cristhiane Ristum
CR
Bagatin
Izabel Yoko
IY
Ito
Marcela Cristina Damião
MC
Andrucioli
Paulo
P
Nelson-Filho
José Tarcísio Lima
JT
Ferreira
D000890:Anti-Infective Agents / Q000737:chemistry*; D002648:Child; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000737:chemistry; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry; D012994:Dental Soldering; D005260:Female; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D009967:Orthodontic Appliances / Q000382:microbiology; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D013052:Spectrometry, X-Ray Emission; D013193:Stainless Steel / Q000737:chemistry; D013997:Time Factors
D000890:Anti-Infective Agents; D003722:Dental Alloys; D013193:Stainless Steel; C010882:chlorhexidine gluconate; D002710:Chlorhexidine