Effect of exogenously applied prostaglandin E2 on alveolar bone loss--histometric analysis

The effect of prostaglandin E2 (PGE2) on alveolar bone resorption was examined in 8-week old Wistar rats by histometric analysis. One mg/ml PGE2 topically applied to gingival sulcus induced a marked increase in osteoclasts. The number of osteoclasts increased progressively and reached a maximum at 12 hours. Ultrastructurally, these osteoclasts were in active form with well developed ruffled borders and clear zones. The changes in numbers of osteoclasts after application of various concentrations of PGE2 were dose-dependent (0.001 to 1.0 mg/ml), but higher concentrations of PGE2 (2 mg/ml) were less effective. In addition, the number of osteoclasts in groups treated with both PGE2 and endotoxin was higher than those that received PGE2 only. These results indicate that bone resorption caused by PGE2 depends on activation and increase of osteoclasts, and suggests that endogenous PGE2 production by host cells stimulated by plaque-associated bacterial endotoxin may be an important pathogenetic factor in periodontal disease.