Bio‐microscopical observation of dystrophic calcification induced by calcium hydroxide

Calcium hydroxide paste was introduced into a rabbit ear chamber, and the effect of calcium hydroxide on the vascular tissue was observed under a biomicroscope continuously up 10 14 weeks. Many precipitates were observed at the border of living tissue, after the dissolution of microvessels around the paste. They increased both in size and number to combine like a river bank in the first 48 h. After 1 week, microcirculation recovered, and newly‐formed capillaries approached the precipitate‐bank, the edge of which became smoother as weeks went by. The bank was stable and compatible to microvessels during the observation period. By SEM observation, the width of the bank was from 200 to 400 μm, and the tissue‐side of the bank appeared like amorphous lamellae, while the inner‐side showed particle‐like appearance. EDX examination revealed high peaks of Ca and P similar to calcium phosphate at the tissue‐side of the bank, but only Ca peak at the inner‐side. The precipitates seemed to have the potential to induce dystrophic calcification by absorbing Ca and P from the tissue.