Detection and parameters of galvanic couples in the oral cavity of patients with orthodontic appliances: a cross-sectional diagnostic study

BACKGROUND: Few publications address the potential development of oral electrogalvanic processes in individuals wearing orthodontic appliances. However, brackets, archwires, and retainers are often fabricated from dissimilar metal alloys, which may lead to the formation of galvanic couples in the oral cavity.

AIM: To assess the risks of electro-galvanic processes during orthodontic treatment of young patients with dentofacial anomalies, depending on the electro-galvanic parameters of components of orthodontic appliances in the oral cavity.

METHODS: Thirty-one patients with various dentofacial anomalies were examined during treatment with fixed orthodontic appliances (bracket systems). Galvanic couples among metallic components of orthodontic appliances (brackets, archwires, retainers) were identified by measuring the electrochemical potentials of each metallic element present intraorally for each patient, followed by calculating potential differences in millivolts (mV). A galvanic couple was considered present if the potential difference exceeded 50 mV. Measurements were obtained using a Fluke 115 multimeter (Fluke, USA). In addition, hydrogen ion concentration (pH) in gingival crevicular fluid adjacent to metallic elements forming galvanic couples was determined with pHSCAN indicator strips (pHSCAN, Russia). Differences in pH values were then calculated; if the difference exceeded 0.6 units, the galvanic couple was classified as active.

RESULTS: Electrochemical potential measurements revealed that most patients (n = 27; 87.1%) did not present galvanic couples. The mean potential difference among appliance components was 27.7 ± 0.9 mV. In contrast, four patients (12.9%) demonstrated supranormal potential differences between archwires and brackets, averaging 66.0 ± 1.5 mV. In these patients, gingival crevicular fluid pH values ranged from 6.4 to 6.8 (mean, 6.60 ± 0.15), with pH differences below 0.6 units in all cases. However, objective evaluation of galvanic couple activity based on pH differences was not feasible because orthodontic components lacked direct contact with the gingival crevice and its fluid.

CONCLUSION: A relatively high frequency of galvanic couples formed by elements of orthodontic appliances was observed (12.9% of patients undergoing orthodontic treatment). Currently, reliable determination of galvanic couple activity during orthodontic treatment remains unavailable; therefore, these patients require increased attention and longitudinal monitoring to detect signs of electrogalvanic processes at an early stage.