The effects of ethylene-1-hydroxy-1, 1-diphosphonate on the developing mandibular condyle -- a light microscopic study.

The effects of high doses of ethylene-1-hydroxy-1, 1-diphosphonate (EHDP), a potential mineralization inhibitor, were studied in the developing mandibular condyle of the rat. The animals were given one injection of EHDP/day for four consecutive days. One group of animals received 30 mg and another group 50 mg EHDP/day. Animals from each group were killed either the day after or three days after the last EHDP-injection. EHDP-administration resulted in a failure of mineralization of the cartilage and osteoid, a widening of the hypertrophic zone, an appearance of cells in lacunae at the cartilage-methphyseal junction and in an inhibited capillary invasion. There was little evidence of a resumed mineralization in rats left to survive for three days after the last EHDP-injection. The results indicate additional effects of EHDP besides an inhibition of calcium phosphate crystallization, and also that EHDP may be a useful tool in the study of mechanisms of cellular hypertrophy and capillary invasion in mineralizing cartilage.