Demonstration and preliminary characterization of bone resorbing activity in freeze-dried gingiva of dogs.

The bone resorbing activity of suspensions or supernatants of freeze-dried powdered gingiva was studied by measuring the release of 45Ca from prelabeled fetal rat long bones in organ culture. Two preparations of noninflamed attached gingiva showed no bone resorbing activity, whereas all six preparations of inflamed marginal gingiva tested showed a dose-related stimulation of 45Ca release. Evidence of an osteoclastic mechanism was provided by the inhibition of the bone resorbing activity by calcitonin and cortisol and the minimal activity observed on dead bones. The activity was heat stable and not blocked by human serum. Three different prostaglandin synthetase inhibitors did not inhibit the activity. Immunoassay showed that PGE was present in gingival powder preparations at concentrations in the range 229-2438 pg/mg dry weight. This was insufficient to account for the observed bone resorbing activity by a factor of 50-350. It was concluded that in addition to PGE, inflamed gingiva contains other heat-stable bone resorbing factor(s).