The multisleeved copper T model TCu220C: effect of long-term use on corrosion and dissolution of copper.

Corrosion and dissolution of copper were studied in 136 multisleeved TCu220C models used for up to 158 months. Surface alterations were examined at low magnification. Topography and depth of copper corrosion were evaluated microscopically in cross-sections of the TCu220C devices. Amounts of residual copper were determined by X-ray fluorescence spectrometry. Sleeve and wire corrosion differ in two respects: edge corrosion is typical for tubular copper and the corrosion process is more pronounced in the upper part of multisleeved devices. Despite considerable individual variation, maximum corrosion depth in relation to duration of IUD use is topographically similar for copper sleeves and copper wire. Calcareous deposits reduce both the dissolution and the corrosion of copper but not the contraceptive effectiveness of the TCu220C. Up to 125 months, the loss of copper from deposit-bearing devices amounts on average to 8 micrograms/day as against 23 micrograms/day for TCu220C models without visible coating.