The occurrence of mononuclear cells at sites of osteoclastic bone resorption in experimental periodontitis.

The placement of silk ligatures around the necks of teeth and into the gingival sulcus causes a rapid, acute inflammatory response leading to vigorous osteoclastic resorption of alveolar crestal bone. Associated with the large numbers of osteoclasts are mononuclear cells, predominantly fibroblast-like cells and macrophages. Some fibroblast-like cells contain intracellular collagen fibrils. It is suggested that in periodontal disease these mononuclear cells may compliment the action of osteoclasts by ingesting and degrading matrix molecules mobilized from bone but not ingested or degraded by osteoclasts.