Effect of Faradic products on direct current-stimulated calvarial organ culture calcium levels

Calcium release from mouse calvarial organ cultures was used to analyse the well-described biological effects of constant direct current (20 mu A) in combination with Faradic products generated at a titanium wire cathode. Constant 20-mu A direct current stimulation alone, delivered by agar salt bridges, consistently lowered the media calcium levels. Direct exposure of calvariae to a titanium cathode and its faradic products resulted in further lowering of media calcium levels and also a significant increase in the media pH. Hydrogen peroxide is a faradic product of the titanium cathode, micromolar amounts being generated by our system over 24 hr. H2O2 is pro-resorptive whereas elevated pH stimulates osteoblast activity. We propose that where bone tissue is in direct contact with metal wire cathodes, the faradic products, hydrogen peroxide and hydroxyl ion, are significant factors which, in their own right, further contribute to accelerated remodelling and improved clinical outcome. (C) 1999 Academic Press.