Caspase-3 as an important factor in the early cytotoxic effect of nickel on oral mucosa cells in patients treated orthodontically.

INTRODUCTION The effect of fixed orthodontic appliances on biochemical changes in saliva and pathophysiological status of the oral cavity is not clear. Recent data showed that nickel (Ni) released from orthodontic appliances can decrease cellular viability, induce DNA damage and apoptosis in oral mucosa cells. Since the mechanism of these Ni effects is unknown, the aim of our study was to analyze the expression of caspase-3 in epithelial cells of oral mucosa in healthy individuals treated orthodontically. MATERIAL AND METHODS Twenty-eight volunteers participated in the study. Epithelial cells were collected from oral mucosa directly before appliance insertion, one week after the insertion, and 24 four weeks after the insertion of fixed appliances. Cellular identification and measurements were conducted by light microscopy. Caspase-3 expression was evaluated immunochemically. Nickel concentration in saliva was also determined. RESULTS A significantly higher number of oral epithelial cells with caspase-3 immunoreactivity in was found one week, but not 24 weeks, after orthodontic treatment. The enhanced expression of caspase-3 was accompanied by increased nickel concentration in saliva. CONCLUSIONS Our data suggests that nickel released from orthodontic appliances can activate caspase-3 and this mechanism may be partially responsible for the cytotoxic action of nickel in the oral cavity of orthodontically-treated individuals.